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Question 91:

Which protocol provides secure management of network devices by encrypting both the session and credentials, replacing unencrypted alternatives like Telnet?

A) SSH
B) HTTP
C) SNMPv2
D) FTP

Answer:

A) SSH

Explanation:

Secure Shell (SSH) is a network protocol designed for secure remote management of devices in enterprise networks, offering encryption for both session data and authentication credentials. SSH addresses vulnerabilities associated with unencrypted protocols such as Telnet, which transmits sensitive information in clear text, making it susceptible to interception and unauthorized access. In enterprise environments where device configuration, monitoring, and troubleshooting are critical, SSH ensures confidentiality, integrity, and authentication across network management operations.

SSH operates using a client-server model, establishing a secure session through a process that includes key exchange, authentication, and encryption. During key exchange, cryptographic algorithms such as Diffie-Hellman generate shared keys between the client and server without transmitting them in plaintext, preventing potential eavesdropping. Authentication can occur via passwords or public/private key pairs, with the latter providing stronger security by eliminating the need to transmit passwords over the network. Once authentication succeeds, the session data, including all commands, responses, and configuration information, is encrypted using symmetric algorithms like AES or 3DES to maintain data confidentiality.

SSH supports additional functionality beyond secure remote access. Port forwarding allows secure tunneling of other network services through the encrypted SSH session. File transfer protocols such as SCP and SFTP enable secure upload and download of configuration files, firmware updates, and backups without exposing sensitive data to interception. SSH also supports session multiplexing, which allows multiple virtual sessions over a single TCP connection, improving operational efficiency and reducing the number of required network connections for administrative tasks.

In enterprise deployments, SSH integrates with AAA services such as TACACS+ or RADIUS, enabling centralized management of user accounts, role-based access control, and detailed logging of administrative actions. This integration supports compliance with security policies, regulatory requirements, and internal operational standards. Network engineers can monitor SSH session activity, enforce access restrictions, and generate reports for auditing and operational oversight. SSH is supported across routers, switches, firewalls, and other network devices, making it a standardized protocol for secure device management in complex networks.

Other options provide different functionality. HTTP offers web-based management but transmits data in clear text unless secured with HTTPS. SNMPv2 allows network monitoring and limited management but lacks robust encryption and authentication. FTP is used for file transfer but does not secure management sessions or encrypt credentials.

For Cisco 350-401 ENCOR exam candidates, understanding SSH involves knowledge of session establishment, key exchange mechanisms, symmetric and asymmetric encryption algorithms, authentication methods, integration with AAA, secure file transfer options, session multiplexing, port forwarding, monitoring and logging practices, verification commands, troubleshooting connectivity issues, and best practices for enterprise deployments. Candidates should be able to configure SSH, enable key-based authentication, restrict access to authorized personnel, monitor session activity, integrate SSH with AAA services, ensure device security, and maintain operational efficiency while managing critical network devices. Mastery of SSH equips network engineers to secure remote management, prevent credential compromise, maintain encrypted communications, and provide reliable administrative access across enterprise networks.

Question 92:

Which technology enables multiple VLANs to be transported across a single physical link between switches while preserving VLAN identification?

A) Trunking
B) Access ports
C) NAT
D) HSRP

Answer:

A) Trunking

Explanation:

Trunking is a Layer 2 technology in enterprise networks that allows multiple VLANs to traverse a single physical link between switches or between a switch and a Layer 3 device. This capability is crucial for networks that deploy multiple VLANs to segment traffic for security, organizational, or service purposes while optimizing physical port utilization. Trunking maintains VLAN identification through tagging mechanisms such as IEEE 802.1Q, ensuring that traffic remains associated with the correct VLAN as it passes across the link.

In 802.1Q trunking, a four-byte tag is inserted into the Ethernet frame, containing VLAN identification and priority information. This allows devices at both ends of the trunk to determine the VLAN to which each frame belongs, enabling proper forwarding and policy enforcement. A native VLAN is configured to carry untagged traffic for devices that do not support VLAN tagging. Proper configuration of native VLANs is critical to prevent VLAN hopping attacks and maintain traffic isolation. Trunks can transport hundreds of VLANs simultaneously, allowing enterprise networks to scale Layer 2 domains efficiently without deploying multiple physical links.

Dynamic Trunking Protocol (DTP) can automate trunk negotiation between Cisco devices, simplifying configuration and ensuring consistency across the network. However, manual trunk configuration is often recommended in production environments to avoid accidental misconfigurations that can cause broadcast storms, loops, or VLAN mismatches. VLAN pruning can be applied to restrict which VLANs traverse a trunk, reducing unnecessary broadcast traffic and optimizing network performance.

Trunking integrates with Layer 3 routing by providing connectivity for inter-VLAN communication. Switches may connect to routers or Layer 3 switches using trunk links to forward traffic between VLANs, enabling centralized routing and policy enforcement. Security policies, QoS mechanisms, and traffic monitoring tools can be applied to trunks to control access, prioritize critical traffic, and maintain visibility into enterprise network operations. Trunks are essential in large-scale campus networks, data centers, and multi-tenant environments, supporting efficient and secure traffic segregation.

Other options provide different functionality. Access ports carry traffic for a single VLAN and cannot transport multiple VLANs. NAT translates IP addresses for connectivity but does not maintain VLAN identification. HSRP provides default gateway redundancy but does not transport VLANs across a single link.

For Cisco 350-401 ENCOR exam candidates, understanding trunking involves knowledge of 802.1Q tagging, VLAN propagation, native VLAN configuration, DTP negotiation, VLAN pruning, inter-VLAN routing, integration with Layer 3 networks, security implications, traffic prioritization, verification commands, troubleshooting mismatched trunks, broadcast storm prevention, and optimization of trunk links for enterprise scalability. Candidates should be able to configure trunk ports, verify VLAN connectivity, enforce security policies, optimize trunk performance, manage multiple VLANs efficiently, and maintain operational stability across the network. Mastery of trunking enables network engineers to implement scalable, secure, and high-performance Layer 2 designs capable of supporting multi-VLAN environments while ensuring seamless connectivity and operational efficiency.

Question 93:

Which protocol provides default gateway redundancy for hosts by electing an active and standby router, ensuring continuous connectivity in case of router failure?

A) HSRP
B) VRF
C) NAT
D) DHCP

Answer:

A) HSRP

Explanation:

Hot Standby Router Protocol (HSRP) is a protocol designed to provide default gateway redundancy for enterprise hosts, ensuring continuous Layer 3 connectivity when a router or link fails. HSRP operates by creating a virtual IP address that hosts use as their default gateway. Among the participating routers, one is elected as the active router responsible for forwarding traffic for the virtual IP, while another router assumes the standby role to take over if the active router becomes unavailable. This mechanism allows hosts to maintain uninterrupted network access without reconfiguring IP addresses or default gateways.

HSRP routers exchange hello messages to monitor the status of active and standby routers. When hello messages from the active router stop arriving, the standby router immediately transitions to the active role, forwarding traffic for the virtual IP. Routers use priority values to determine which router should become active in the event of multiple candidates. Preemption can be configured to allow a higher-priority router to regain the active role after recovering from a failure. Multiple HSRP groups can be deployed across different VLANs to achieve redundancy and load sharing, ensuring that traffic is distributed efficiently while maintaining high availability.

HSRP timers, including hello interval and hold time, control the failover speed. Proper configuration of these timers ensures low-latency failover, which is critical for time-sensitive applications such as VoIP, video streaming, and transaction systems. Integration with VLANs ensures that each Layer 3 segment maintains gateway redundancy. HSRP also works with routing protocols to ensure optimal path selection and minimal disruption during failover events, maintaining consistent connectivity across the enterprise network.

Other options provide different functionality. VRF isolates routing instances but does not provide gateway redundancy. NAT translates addresses for external communication but does not maintain continuous default gateway availability. DHCP dynamically assigns IP addresses but does not offer failover functionality for default gateways.

For Cisco 350-401 ENCOR exam candidates, understanding HSRP involves knowledge of active and standby roles, priority configuration, preemption, virtual IP and MAC addresses, multiple HSRP groups, VLAN integration, failover detection, timers, verification commands, load balancing, interaction with routing protocols, troubleshooting connectivity during failures, and maintaining seamless access for end devices. Candidates should be able to configure HSRP, verify failover behavior, optimize convergence times, maintain continuous network availability, and support multiple VLANs and enterprise applications. Mastery of HSRP allows network engineers to deploy resilient Layer 3 networks, ensure uninterrupted service, distribute traffic across multiple routers, and meet enterprise requirements for high availability and operational reliability.

Question 94:

Which protocol is used to securely synchronize the time across network devices in an enterprise environment, ensuring accurate timestamps for logs and events?

A) NTP
B) SNMP
C) HSRP
D) FTP

Answer:

A) NTP

Explanation:

Network Time Protocol (NTP) is an essential protocol in enterprise networks that allows devices to synchronize their internal clocks accurately across potentially complex network topologies. Accurate timekeeping is critical for multiple network functions, including log correlation, security event tracking, authentication protocols, and time-sensitive applications. NTP provides mechanisms to ensure that all devices, including routers, switches, firewalls, and servers, maintain a consistent notion of time.

NTP operates using a hierarchical architecture consisting of stratum levels. Stratum 0 devices, such as atomic clocks and GPS receivers, serve as highly accurate time sources. Stratum 1 servers are directly connected to stratum 0 devices and provide accurate time to other devices. Stratum 2 and lower servers synchronize their clocks with higher-stratum devices, propagating consistent time information throughout the network. NTP uses timestamps and algorithms to measure the delay between client and server communication, adjusting the local clock gradually to avoid sudden jumps that could disrupt time-sensitive processes.

Security is a key concern in NTP deployment. NTP authentication using symmetric keys or autokey cryptography ensures that time information originates from trusted sources, preventing malicious entities from injecting incorrect time values, which could impact logging, certificate validation, or application behavior. NTP also supports monitoring of offset and delay metrics, allowing administrators to verify synchronization accuracy and detect anomalies. Redundant NTP servers can be configured to enhance reliability and ensure that devices maintain accurate time even if one server becomes unavailable.

Integration with enterprise management systems is an important aspect of NTP. Logs collected from devices often rely on timestamps for correlation in security information and event management (SIEM) tools. Time inconsistencies can make troubleshooting network incidents, auditing, and compliance reporting challenging. NTP also supports various modes, including client-server, peer-to-peer, broadcast, and multicast, providing flexible deployment options for different network architectures, from small LANs to large-scale WANs.

Other options provide different functionality. SNMP is used for network monitoring and device management but does not synchronize time. HSRP provides default gateway redundancy but does not manage device clocks. FTP is a file transfer protocol that does not deal with time synchronization.

For Cisco 350-401 ENCOR exam candidates, understanding NTP involves knowledge of stratum hierarchy, time offset calculation, delay measurement, clock adjustment algorithms, authentication mechanisms, peer and server configuration, broadcast and multicast modes, monitoring and troubleshooting techniques, redundancy deployment, integration with logging and SIEM systems, verification commands, network security considerations, and ensuring consistent time across all devices. Candidates should be able to configure NTP on Cisco routers and switches, verify synchronization status, monitor accuracy, detect drift or offset issues, integrate NTP with enterprise security policies, and maintain reliable timekeeping for operational and security purposes. Mastery of NTP enables network engineers to ensure accurate timestamps for all network events, maintain operational consistency, and provide precise timing required for critical enterprise applications.

Question 95:

Which enterprise routing protocol uses link-state information to calculate the shortest path for packet forwarding, allowing fast convergence in large networks?

A) OSPF
B) RIP
C) EIGRP
D) BGP

Answer:

A) OSPF

Explanation:

Open Shortest Path First (OSPF) is a widely used interior gateway protocol (IGP) in enterprise networks, known for its ability to efficiently compute optimal routing paths using link-state information. Unlike distance-vector protocols, which rely on hop counts and periodic updates, OSPF maintains a complete map of the network topology, allowing routers to make informed forwarding decisions based on the shortest path to each destination. The link-state database, shared among all OSPF routers within an area, contains detailed information about router interfaces, link costs, and network connectivity.

OSPF organizes networks into areas to optimize scalability and reduce processing overhead. Area 0, or the backbone area, forms the core of an OSPF domain, with all other areas connecting to it. This hierarchical design reduces the size of routing tables and limits the scope of link-state advertisements (LSAs) to individual areas, enhancing convergence times and resource utilization. OSPF routers exchange LSAs using the flooding mechanism, ensuring that all routers within an area have an identical view of the network topology.

Fast convergence is a critical advantage of OSPF, particularly in enterprise environments where link failures, device reboots, or topology changes occur frequently. OSPF recalculates the shortest path using Dijkstra’s algorithm whenever the network topology changes, updating the forwarding table almost immediately. This ensures minimal disruption to application traffic, maintaining operational performance for latency-sensitive services such as VoIP and video conferencing. OSPF also supports equal-cost multi-path (ECMP) routing, allowing traffic to be balanced across multiple optimal paths for better bandwidth utilization and redundancy.

OSPF supports authentication to prevent unauthorized devices from injecting false routing information. Simple password authentication or cryptographic authentication using MD5 can be configured between OSPF neighbors, ensuring that LSAs are only accepted from trusted routers. OSPF integrates with VLANs, point-to-point links, and WAN connections, supporting both IPv4 and IPv6 routing, and allowing enterprise networks to deploy a consistent, scalable routing protocol across heterogeneous topologies.

Other options provide different functionalities. RIP uses hop count metrics and converges slowly in large networks. EIGRP is a hybrid protocol that provides fast convergence but relies on Cisco proprietary mechanisms. BGP is an exterior gateway protocol designed for inter-domain routing and is not optimized for internal enterprise routing.

For Cisco 350-401 ENCOR exam candidates, understanding OSPF involves knowledge of link-state operation, LSA types, area configuration, backbone design, neighbor relationships, authentication, SPF calculations, convergence behavior, equal-cost path load balancing, verification and troubleshooting commands, interface configuration, area summarization, and route redistribution. Candidates should be able to configure OSPF, verify neighbor adjacency, monitor link-state databases, troubleshoot routing inconsistencies, optimize topology design, implement authentication, and maintain reliable and efficient routing across enterprise networks. Mastery of OSPF enables network engineers to design scalable, robust, and high-performance routing infrastructures that adapt rapidly to changes and provide optimal path selection for enterprise traffic.

Question 96:

Which protocol is used by enterprise networks to automatically discover devices on the same Layer 2 network and share information about their capabilities, such as IP address, device type, and platform?

A) CDP
B) HSRP
C) DHCP
D) NAT

Answer:

A) CDP

Explanation:

Cisco Discovery Protocol (CDP) is a proprietary Layer 2 protocol used in enterprise networks to enable devices to discover each other and share information about their hardware and software capabilities. CDP allows routers, switches, and other Cisco devices to advertise device identity, IP addresses, interface information, platform type, and software version to directly connected neighbors. This capability is essential for network mapping, inventory management, troubleshooting, and topology validation in complex enterprise environments.

CDP operates by periodically sending advertisements to multicast addresses at Layer 2, ensuring that neighboring devices receive information about the sending device. Each device maintains a CDP table containing information about all discovered neighbors, including device ID, IP addresses, software version, capabilities, and interface identifiers. This data can be used by network engineers to visualize network topology, detect misconfigurations, validate device interconnections, and monitor network health. CDP also supports enhanced features such as CDP advertisements over trunk links, enabling multi-VLAN discovery and more comprehensive mapping of enterprise networks.

CDP integrates with other Cisco features to provide operational insights. For example, CDP information can be used by network management tools to populate device databases automatically, reducing manual effort and errors in network documentation. CDP can also provide details for neighbor troubleshooting, including interface mismatches, duplex or speed inconsistencies, and hardware platform identification. This allows administrators to proactively address issues before they impact network performance. CDP messages contain device capability information, which can include router, switch, voice gateway, IP phone, or access point functionality, enabling intelligent decisions about network deployment, segmentation, and management.

Other options provide different functionalities. HSRP ensures gateway redundancy but does not enable device discovery. DHCP dynamically assigns IP addresses but does not advertise device information. NAT translates addresses for connectivity but does not provide device visibility or network mapping.

For Cisco 350-401 ENCOR exam candidates, understanding CDP involves knowledge of periodic advertisement intervals, neighbor table management, device capabilities advertisement, interface information, CDP over trunk and access links, integration with management tools, troubleshooting misconfigurations, verifying topology connectivity, identifying network devices and platforms, monitoring changes in the network, and ensuring accurate documentation. Candidates should be able to configure CDP, enable or disable it per interface, interpret CDP neighbor information, troubleshoot connectivity issues, and leverage CDP for operational visibility and management. Mastery of CDP enables network engineers to maintain accurate network topology awareness, facilitate device management, optimize inter-device communication, enhance troubleshooting efficiency, and support operational reliability across enterprise networks.

Question 97:

Which enterprise network technology allows multiple virtual routing and forwarding instances on a single physical router, enabling overlapping IP addresses in different segments?

A) VRF
B) OSPF
C) NAT
D) HSRP

Answer:

A) VRF

Explanation:

Virtual Routing and Forwarding (VRF) is a key technology in enterprise networks that enables the creation of multiple logical routing tables on a single physical router. Each VRF instance functions as an independent routing domain, allowing the same IP address space to be used in multiple segments without conflict. This capability is particularly useful in large enterprise networks with overlapping networks, multi-tenant environments, service provider integrations, and scenarios requiring traffic isolation. By maintaining separate routing instances, VRF provides logical separation, simplifies network management, and enhances security by ensuring that traffic from one VRF cannot directly communicate with another VRF unless explicitly configured.

VRF operates by maintaining separate routing tables and forwarding tables for each instance. Packets arriving on an interface associated with a particular VRF are processed according to the VRF-specific routing table. Interfaces, subinterfaces, or even VLANs can be associated with VRF instances to ensure that the traffic entering or leaving the device is directed appropriately. This separation allows administrators to implement distinct policies, security controls, and quality-of-service configurations for different VRFs. VRF also supports route leaking, where specific routes can be shared between VRFs using import/export configurations. This provides controlled connectivity between segments while maintaining logical separation for the rest of the traffic.

VRF is extensively used in enterprise WAN designs, data centers, and service provider environments. In WAN scenarios, multiple customer networks can be supported over a single router without risk of IP overlap, enabling efficient utilization of hardware resources. In data centers, VRF allows segmentation of production, testing, and management networks, improving operational control and security. VRF integration with MPLS expands its capabilities, providing scalable, isolated routing across wide-area networks and service provider infrastructures. Additionally, VRF supports IPv4 and IPv6 routing, static and dynamic routing protocols, and integration with multicast traffic for enterprise applications requiring separate forwarding domains.

Operational and troubleshooting aspects of VRF include verifying VRF-specific routing tables, interface association, route leaking configuration, and connectivity testing across VRF instances. Network engineers must understand the implications of VRF on routing protocol advertisements, access control policies, and NAT integration. VRF also interacts with Layer 2 technologies like VLANs and trunking, ensuring that network segmentation is maintained across the physical and logical infrastructure. Proper implementation of VRF ensures scalability, security, traffic isolation, and resource optimization, making it a cornerstone of modern enterprise routing design.

Other options provide different functionalities. OSPF is a routing protocol but does not inherently separate traffic into multiple independent routing instances. NAT translates addresses for connectivity purposes but does not provide isolated routing tables. HSRP provides default gateway redundancy but does not segment routing domains.

For Cisco 350-401 ENCOR exam candidates, understanding VRF involves knowledge of creating and associating VRF instances, interface assignment, separate routing tables, route leaking mechanisms, integration with VLANs, MPLS, and WAN designs, verification commands, troubleshooting inter-VRF connectivity, operational best practices, interaction with dynamic routing protocols, multicast handling, and traffic isolation techniques. Candidates should be able to configure VRF, verify routing and forwarding behavior per VRF, implement controlled route sharing, maintain network segmentation, and optimize hardware resources while supporting multiple logical networks on a single physical device. Mastery of VRF allows network engineers to deploy secure, scalable, and flexible routing solutions in complex enterprise and multi-tenant environments, ensuring operational efficiency, traffic isolation, and compatibility with advanced routing designs.

Question 98:

Which Cisco enterprise protocol ensures the rapid detection of Layer 2 link failures and minimizes downtime by quickly transitioning ports to forwarding state?

A) RSTP
B) STP
C) HSRP
D) CDP

Answer:

A) RSTP

Explanation:

Rapid Spanning Tree Protocol (RSTP) is an enhancement of the original Spanning Tree Protocol (STP) that allows enterprise networks to detect Layer 2 link failures and reconverge network topology significantly faster. In traditional STP, convergence can take up to 50 seconds or longer, which can disrupt time-sensitive applications such as VoIP, video streaming, and transactional systems. RSTP addresses this by introducing new port roles and states, reducing the time required to transition ports from blocking to forwarding.

RSTP operates using the same fundamental loop-prevention principles as STP, including root bridge election, path cost calculation, and topology determination. However, RSTP introduces new port types, including alternate and backup ports, which allow immediate backup paths to be activated when a primary link fails. Alternate ports provide a pre-designated path to the root bridge in case the current root port fails, while backup ports maintain connectivity for redundant segments. These mechanisms minimize downtime by ensuring that alternative paths are available without waiting for timer-based transitions that STP relies on.

RSTP also modifies the handshake process between neighboring switches, allowing faster negotiation of port roles and states. The proposal-agreement mechanism allows switches to determine immediately which ports should be placed in forwarding or discarding states, further reducing convergence time. Edge ports, which are directly connected to end devices and do not create loops, can transition to forwarding state immediately without participating in the standard negotiation process. This behavior is similar to PortFast in STP, providing rapid connectivity for hosts.

RSTP integrates with VLANs and supports multiple spanning tree instances when combined with MSTP for enterprise networks that require scalable multi-VLAN deployments. Administrators can monitor port roles, state changes, and neighbor relationships using verification commands, enabling proactive management and troubleshooting. RSTP ensures that redundant links remain available while preventing loops and broadcast storms, optimizing network performance, and supporting high availability in modern enterprise networks.

Other options provide different functionalities. STP prevents loops but converges slowly compared to RSTP. HSRP provides default gateway redundancy but does not manage Layer 2 topology or link failure detection. CDP enables neighbor discovery but does not handle loop prevention or fast failover.

For Cisco 350-401 ENCOR exam candidates, understanding RSTP involves knowledge of port roles (root, designated, alternate, backup, edge), port states (discarding, learning, forwarding), root bridge election, path cost calculation, proposal-agreement handshakes, rapid topology changes, integration with VLANs and MSTP, timer management, loop prevention mechanisms, convergence optimization, verification commands, troubleshooting techniques, monitoring link failures, network performance management, and deployment best practices. Candidates should be able to configure RSTP on enterprise switches, verify port roles and states, monitor topology changes, troubleshoot network connectivity issues, optimize redundant links for performance and availability, and maintain a loop-free network with rapid recovery from link failures. Mastery of RSTP enables network engineers to design resilient, high-performance Layer 2 networks capable of supporting modern enterprise applications and critical services with minimal disruption.

Question 99:

Which Cisco protocol is designed to provide network traffic classification and quality of service by marking packets with priority values for enterprise applications?

A) CoS
B) HSRP
C) NAT
D) OSPF

Answer:

A) CoS

Explanation:

Class of Service (CoS) is a Layer 2 mechanism in enterprise networks used to classify and prioritize traffic based on predefined policies, ensuring that critical applications receive appropriate bandwidth and minimal delay. CoS marks packets with priority values in the IEEE 802.1Q header, allowing switches and other network devices to make forwarding and queuing decisions that maintain performance for latency-sensitive services such as voice, video, and mission-critical data. By enabling traffic differentiation at the Layer 2 level, CoS ensures predictable network behavior, reduces congestion, and maintains operational efficiency across complex enterprise infrastructures.

CoS operates using a three-bit field in the 802.1Q VLAN tag, which allows eight priority levels ranging from 0 (lowest priority) to 7 (highest priority). Network devices use these values to map traffic into queues, schedule transmissions, and implement congestion avoidance mechanisms. For example, voice traffic may be assigned the highest priority to minimize jitter and latency, while bulk file transfers may be assigned a lower priority to prevent them from interfering with time-sensitive applications. CoS integrates with queuing mechanisms such as Weighted Fair Queuing (WFQ), Priority Queuing (PQ), and Low Latency Queuing (LLQ) to manage traffic effectively and enforce service-level objectives.

In enterprise networks, CoS can be used in combination with Layer 3 QoS policies, such as Differentiated Services Code Point (DSCP) markings, to provide end-to-end service quality across routed and switched segments. CoS enables traffic shaping, policing, and prioritization within VLANs, ensuring that high-priority applications maintain performance even during periods of congestion. Network engineers can monitor and verify CoS behavior using traffic counters, queue statistics, and policy verification commands, ensuring that the intended policies are effectively enforced across the network.

Other options provide different functionalities. HSRP ensures default gateway redundancy but does not classify or prioritize traffic. NAT translates addresses but does not provide traffic prioritization. OSPF is a routing protocol that does not manage traffic queues or prioritization.

For Cisco 350-401 ENCOR exam candidates, understanding CoS involves knowledge of 802.1Q header structure, priority levels, queue management, scheduling algorithms, integration with VLANs, interaction with Layer 3 QoS, traffic shaping and policing, verification commands, monitoring tools, troubleshooting techniques, policy enforcement, end-to-end QoS deployment, and support for critical enterprise applications. Candidates should be able to configure CoS, map traffic classes to priority queues, implement queuing policies, monitor and verify traffic behavior, troubleshoot policy enforcement issues, optimize bandwidth utilization, and maintain high performance for latency-sensitive applications. Mastery of CoS allows network engineers to deliver predictable and reliable network performance, support real-time applications, optimize resource utilization, and ensure operational efficiency across enterprise networks.

Question 100:

Which technology allows multiple Layer 2 networks to be carried over a single Layer 3 network infrastructure while preserving VLAN separation in enterprise environments?

A) VXLAN
B) MPLS
C) HSRP
D) NAT

Answer:

A) VXLAN

Explanation:

Virtual Extensible LAN (VXLAN) is a network virtualization technology designed to extend Layer 2 segments across Layer 3 networks, enabling scalable enterprise and data center deployments. VXLAN encapsulates Ethernet frames within UDP packets, which allows traffic from multiple VLANs to traverse an IP-based Layer 3 infrastructure without losing VLAN separation. This technology addresses limitations of traditional VLANs, which are constrained by a maximum of 4096 identifiers, and provides a solution for large-scale multi-tenant networks that require thousands of isolated segments.

VXLAN operates by introducing a VXLAN Network Identifier (VNI), which uniquely identifies each logical Layer 2 network within the Layer 3 transport. Network devices, such as VXLAN Tunnel Endpoints (VTEPs), encapsulate original Ethernet frames with a VXLAN header containing the VNI and transmit the encapsulated packets across the Layer 3 network using UDP. At the receiving end, the VTEP decapsulates the packet and forwards the original Ethernet frame to the appropriate VLAN segment. This approach allows enterprises to scale networks across multiple data centers, maintain tenant isolation, and optimize IP infrastructure utilization while preserving Layer 2 semantics for applications that require broadcast or multicast traffic.

VXLAN integrates with routing and switching infrastructure, supporting both unicast and multicast modes for efficient packet delivery. In multicast mode, VXLAN uses IP multicast to distribute broadcast, unknown unicast, and multicast (BUM) traffic, reducing flooding and ensuring efficient bandwidth usage. In unicast mode, VXLAN employs head-end replication, where the originating VTEP replicates BUM traffic to other VTEPs, allowing operation without multicast support in the underlying network. VXLAN is widely adopted in modern data center architectures, cloud deployments, and enterprise environments requiring scalable, isolated, and flexible network segmentation.

Operational deployment involves configuring VTEPs, mapping VLANs to VXLAN VNIs, verifying encapsulation and decapsulation behavior, and monitoring BUM traffic efficiency. VXLAN integrates with Layer 3 routing protocols such as OSPF, BGP, or IS-IS to provide IP connectivity between VTEPs, enabling multi-site deployments and dynamic routing across the network. Security considerations include implementing access control lists, isolation policies, and encryption mechanisms to ensure that tenant or department traffic remains private and secure across shared infrastructure. Network engineers must monitor VXLAN performance, optimize encapsulation efficiency, troubleshoot connectivity issues, and ensure proper VNI mappings to maintain operational integrity and support critical enterprise applications.

Other options provide different functionalities. MPLS is primarily a Layer 3 traffic engineering and forwarding mechanism, not specifically designed to extend Layer 2 networks. HSRP provides gateway redundancy but does not enable Layer 2 over Layer 3 transport. NAT translates IP addresses for connectivity but does not support Layer 2 extension or segmentation.

For Cisco 350-401 ENCOR exam candidates, understanding VXLAN involves knowledge of VTEP configuration, VNI mapping, encapsulation and decapsulation process, multicast and unicast modes, integration with routing protocols, troubleshooting and verification techniques, security policies, scalability considerations, support for multi-tenant environments, monitoring tools, performance optimization, VLAN-to-VXLAN mapping, BUM traffic handling, and operational best practices. Candidates should be able to deploy VXLAN in enterprise networks, verify connectivity, maintain VLAN separation, manage large-scale network segmentation, optimize traffic flow, and support applications requiring Layer 2 connectivity across Layer 3 infrastructure. Mastery of VXLAN enables network engineers to build flexible, scalable, and secure enterprise networks capable of supporting high-performance applications and multi-tenant architectures.

Question 101:

Which routing protocol is designed for exchanging routes between different autonomous systems and is widely used to connect enterprise networks to service providers?

A) BGP
B) OSPF
C) EIGRP
D) RIP

Answer:

A) BGP

Explanation:

Border Gateway Protocol (BGP) is the primary protocol used for inter-domain routing, allowing networks in different autonomous systems (AS) to exchange routing information. BGP is crucial in enterprise networks that connect to Internet service providers or operate multiple autonomous systems for organizational segmentation, redundancy, and scalability. BGP provides policy-based routing, allowing administrators to control path selection based on attributes such as AS path, local preference, MED, and community values.

BGP operates as a path vector protocol, maintaining a table of network paths along with attributes associated with each path. BGP peers, known as neighbors, establish TCP sessions over port 179 to exchange routing updates. The protocol ensures loop prevention by including the AS path in routing updates, allowing routers to detect and reject routes that would create loops across autonomous systems. BGP also supports incremental updates, reducing bandwidth usage by sending only changes rather than the entire routing table.

BGP provides mechanisms for route aggregation, route filtering, and traffic engineering. Aggregation allows multiple prefixes to be represented as a single route, reducing the size of routing tables. Route filtering controls which prefixes are advertised or accepted from peers, ensuring that unwanted routes do not propagate into the network. Traffic engineering using BGP attributes enables enterprises to influence the path traffic takes across multiple providers, optimize bandwidth utilization, and maintain high availability.

In enterprise WAN deployments, BGP often operates alongside internal routing protocols such as OSPF or EIGRP, providing connectivity between internal networks and external service providers. Route redistribution between internal and external protocols must be carefully configured to avoid routing loops and maintain consistent path selection. BGP supports both IPv4 and IPv6 routing and can scale to handle large numbers of prefixes, making it suitable for connecting enterprise networks to global Internet routing infrastructure.

Operational considerations include monitoring neighbor relationships, verifying routing updates, troubleshooting path selection issues, ensuring security through authentication and prefix filtering, and maintaining high availability through redundant BGP sessions. Network engineers must understand BGP path selection rules, route advertisement policies, convergence behavior, and integration with enterprise WAN designs to optimize connectivity and resilience.

Other options provide different functionalities. OSPF and EIGRP are interior gateway protocols used within a single AS and are not designed for inter-AS routing. RIP is a legacy distance-vector protocol unsuitable for modern enterprise or Internet-scale deployments.

For Cisco 350-401 ENCOR exam candidates, understanding BGP involves knowledge of autonomous systems, peer establishment, path vector operation, routing attributes, loop prevention, incremental updates, route filtering, aggregation, redistribution, traffic engineering, neighbor verification, troubleshooting, IPv4 and IPv6 support, convergence behavior, policy configuration, redundancy design, and operational monitoring. Candidates should be able to configure BGP peers, verify path selection, implement routing policies, troubleshoot connectivity, maintain high availability, optimize enterprise-to-provider connections, and ensure reliable routing across inter-domain networks. Mastery of BGP allows network engineers to control traffic across autonomous systems, influence route selection, maintain secure and scalable enterprise connectivity, and support critical WAN and Internet-facing operations.

Question 102:

Which protocol enables secure authentication, authorization, and accounting for network devices, providing centralized control over administrative access in enterprise networks?

A) TACACS+
B) SNMP
C) HSRP
D) NTP

Answer:

A) TACACS+

Explanation:

Terminal Access Controller Access-Control System Plus (TACACS+) is a protocol used to provide centralized authentication, authorization, and accounting (AAA) for network devices in enterprise environments. TACACS+ enhances security by encrypting the entire payload of administrative sessions, including user credentials and commands, unlike protocols such as RADIUS, which only encrypt the password. Centralized AAA control allows organizations to manage access to routers, switches, firewalls, and other devices consistently while maintaining detailed audit logs for compliance, operational monitoring, and forensic purposes.

TACACS+ operates using a client-server model where network devices act as clients and a centralized TACACS+ server handles authentication and authorization requests. The protocol uses TCP port 49 for reliable transport and supports command-level authorization, enabling granular control over which commands a user can execute. This allows network administrators to implement role-based access control, granting different privileges to different users based on their responsibilities. Accounting features capture detailed logs of commands executed, session start and stop times, and any configuration changes, providing full visibility into administrative activity.

TACACS+ integrates with enterprise directory services such as LDAP or Active Directory, allowing network authentication policies to align with organizational identity management systems. Redundant TACACS+ servers can be deployed to ensure high availability and maintain consistent access even during server failures. Security features include support for encrypted communication, key rotation, secure user credential storage, and detailed logging for audit purposes. TACACS+ also allows centralized policy enforcement, ensuring that all network devices adhere to consistent access control practices, reducing the risk of unauthorized configuration changes or policy violations.

Other options provide different functionalities. SNMP is used for device monitoring and management but does not provide centralized authentication and command-level authorization. HSRP ensures default gateway redundancy but does not handle AAA. NTP synchronizes device clocks but does not control administrative access or provide accounting capabilities.

For Cisco 350-401 ENCOR exam candidates, understanding TACACS+ involves knowledge of AAA architecture, client-server interactions, TCP transport, authentication mechanisms, role-based access control, command authorization, accounting and logging practices, server redundancy, integration with directory services, encryption of session data, verification commands, troubleshooting authentication issues, audit logging, policy enforcement, session management, and security best practices. Candidates should be able to configure TACACS+ on enterprise devices, assign users and roles, monitor administrative activity, troubleshoot access problems, implement redundancy, secure communication between devices and servers, maintain operational consistency, and ensure compliance with enterprise security policies. Mastery of TACACS+ enables network engineers to provide secure, centralized administrative access, protect network devices from unauthorized changes, maintain detailed logs for auditing, enforce operational policies consistently, and support high availability and scalability across enterprise networks.

Question 103:

Which Cisco technology provides network segmentation and policy enforcement at the access layer by assigning devices to virtual networks based on authentication and device characteristics?

A) Cisco ISE
B) CoS
C) NAT
D) OSPF

Answer:

A) Cisco ISE

Explanation:

Cisco Identity Services Engine (ISE) is a policy-based access control platform used in enterprise networks to enforce security and segmentation at the access layer. ISE enables organizations to identify devices, authenticate users, and assign them to appropriate virtual networks based on predefined policies. The system supports multiple authentication methods, including 802.1X, MAC authentication bypass (MAB), and web authentication, allowing both wired and wireless devices to be integrated into the enterprise network securely. By integrating with network devices such as switches, wireless controllers, and firewalls, ISE dynamically controls access based on identity, device type, location, and security posture.

ISE operates by creating a centralized policy framework that evaluates incoming requests against authentication and authorization rules. For example, a corporate laptop might be assigned to a secure VLAN with full access to internal applications, whereas a guest device could be restricted to an isolated network segment with internet-only access. Policies can include device profiling to detect endpoint types, operating systems, and security attributes, enabling administrators to enforce differentiated access for managed, unmanaged, or bring-your-own-device (BYOD) endpoints. ISE integrates with other security tools such as antivirus, posture assessment, and endpoint compliance systems to ensure that only authorized devices and users gain appropriate network access.

The technology also supports centralized monitoring and logging, capturing detailed records of authentication attempts, authorization decisions, and policy violations. Administrators can leverage these logs to investigate security incidents, monitor compliance, and optimize access policies. ISE provides integration with RADIUS and TACACS+ protocols, allowing granular control over administrative access to network devices, which complements its endpoint access enforcement capabilities. Network engineers can configure dynamic VLAN assignment, downloadable access control lists (dACLs), and policy-based access control (PBAC) to ensure consistent enforcement across the network.

ISE supports scalable deployments, allowing distributed policy enforcement across multiple sites while maintaining centralized management. Redundant deployment options ensure high availability, and integration with network devices through pxGrid facilitates automated threat response and adaptive security policies. Operational procedures include monitoring authentication success and failure rates, validating device profiling accuracy, verifying VLAN assignments, troubleshooting access issues, and optimizing policy performance to support high-density enterprise environments.

Other options provide different functionalities. CoS classifies traffic for quality of service but does not assign devices to virtual networks based on authentication. NAT translates addresses for connectivity but does not provide access control or policy enforcement. OSPF is a routing protocol and does not manage device access or network segmentation.

For Cisco 350-401 ENCOR exam candidates, understanding ISE involves knowledge of authentication methods, policy creation, device profiling, VLAN assignment, dACL configuration, RADIUS and TACACS+ integration, pxGrid interactions, monitoring and logging capabilities, compliance enforcement, guest access management, BYOD integration, operational verification commands, troubleshooting procedures, high availability design, endpoint security integration, dynamic access control, network device integration, and adaptive policy implementation. Candidates should be able to deploy ISE in enterprise networks, configure policies for different device types, verify access enforcement, troubleshoot authentication and authorization issues, integrate with security tools, monitor compliance, implement high availability, and ensure that segmentation policies are consistently applied to maintain secure network access. Mastery of ISE enables network engineers to enforce granular access control, secure endpoints, isolate sensitive resources, monitor policy compliance, and support modern enterprise access requirements.

Question 104:

Which routing protocol is specifically designed to provide loop-free, fast-converging, and scalable interior routing in large enterprise networks while supporting variable-length subnet masks and route summarization?

A) OSPF
B) RIP
C) EIGRP
D) BGP

Answer:

C) EIGRP

Explanation:

Enhanced Interior Gateway Routing Protocol (EIGRP) is a Cisco proprietary routing protocol that combines features of distance-vector and link-state protocols to deliver loop-free, fast-converging, and scalable routing within an autonomous system. EIGRP uses the Diffusing Update Algorithm (DUAL) to calculate loop-free paths to all destinations and maintain consistent routing tables, which allows for rapid convergence following topology changes. The protocol supports classless routing, enabling the use of variable-length subnet masks (VLSM), which optimizes IP address allocation and improves address utilization in large enterprise networks.

EIGRP maintains multiple tables to manage routing information. The neighbor table tracks directly connected routers with whom the protocol exchanges updates. The topology table stores all learned routes along with feasibility distances, reported distances, and route metrics. The routing table contains only the best paths to each destination, as determined by DUAL. Feasible successors provide backup routes that can be activated immediately if the primary path fails, ensuring minimal downtime and fast recovery in complex networks.

EIGRP calculates metrics based on bandwidth, delay, reliability, and load, allowing network engineers to fine-tune path selection based on network performance and operational requirements. Route summarization reduces routing table size and optimizes network resource usage by aggregating multiple subnets into a single advertised route. EIGRP supports both IPv4 and IPv6, enhancing flexibility in modern enterprise networks. Operational deployment includes configuring autonomous system numbers, interface participation, authentication between neighbors, route redistribution with other protocols, and verification using show commands to monitor neighbor relationships, route metrics, and convergence behavior.

EIGRP provides advanced features such as unequal-cost load balancing, allowing traffic to be distributed across multiple paths based on relative metrics, improving network utilization and redundancy. It also integrates with security mechanisms such as authentication to ensure that only authorized routers participate in routing exchanges. Troubleshooting EIGRP requires analyzing neighbor relationships, topology tables, feasibility conditions, and convergence behavior to identify misconfigurations or network issues. Network engineers must understand the impact of timers, hello and hold intervals, stub routing, and split-horizon rules on overall network operation to maintain optimal performance and scalability.

Other options provide different functionalities. OSPF is a link-state protocol that supports scalable routing but uses a different convergence mechanism and database synchronization. RIP is a distance-vector protocol with slower convergence and limited scalability. BGP is designed for inter-domain routing and does not optimize interior network path selection.

For Cisco 350-401 ENCOR exam candidates, understanding EIGRP involves knowledge of DUAL operation, metric calculation, neighbor and topology table management, feasible successors, route summarization, unequal-cost load balancing, authentication, IPv4 and IPv6 support, interface configuration, autonomous system management, convergence optimization, route redistribution, troubleshooting techniques, monitoring commands, timer configuration, stub routing, split-horizon handling, and operational best practices. Candidates should be able to configure EIGRP on enterprise routers, verify routing information, monitor convergence, implement route summarization, troubleshoot connectivity issues, optimize path selection, secure routing exchanges, manage scalable enterprise networks, and ensure fast recovery from topology changes. Mastery of EIGRP enables network engineers to maintain reliable, loop-free, and high-performance routing within large enterprise networks, optimize resource utilization, support multi-site connectivity, and provide robust fault-tolerant network operation.

Question 105:

Which Cisco enterprise protocol provides rapid failover for gateway redundancy by allowing multiple routers to share a virtual IP address while maintaining consistent network availability?

A) HSRP
B) VRRP
C) GLBP
D) STP

Answer:

A) HSRP

Explanation:

Hot Standby Router Protocol (HSRP) is a Cisco proprietary protocol designed to provide high availability for default gateways in enterprise networks. HSRP allows multiple routers to share a virtual IP address and virtual MAC address, creating a single logical gateway for end devices. In this configuration, one router is designated as the active router, responsible for forwarding traffic, while another router is designated as the standby router, ready to take over in case the active router fails. This redundancy ensures continuous network connectivity and minimizes service disruptions for end users.

HSRP operates by exchanging hello messages between participating routers to monitor their status. The active router handles all traffic for the virtual IP, while the standby router monitors the active router’s availability. If the active router fails or becomes unreachable, the standby router immediately assumes the role of active router, maintaining the virtual IP and MAC addresses so that hosts do not need to update their default gateway configuration. HSRP timers, including hello and hold intervals, determine the speed at which failover occurs, allowing network engineers to tune the protocol for faster recovery in critical environments.

HSRP also supports multiple groups, allowing network designers to configure redundancy for different VLANs or segments independently. Load balancing can be achieved by configuring multiple HSRP groups across different routers, enabling traffic distribution while maintaining high availability. HSRP integrates with network monitoring tools to provide visibility into router status, priority configuration, preemption, and failover behavior, which helps network engineers detect issues and optimize gateway redundancy. Security features such as authentication protect HSRP messages from being spoofed or manipulated by unauthorized devices.

Other options provide different functionalities. VRRP is an open-standard gateway redundancy protocol, similar in operation to HSRP but not Cisco-specific. GLBP allows automatic load balancing among multiple routers for a single virtual IP. STP is a Layer 2 protocol used for loop prevention and does not provide gateway redundancy or failover capabilities.

For Cisco 350-401 ENCOR exam candidates, understanding HSRP involves knowledge of virtual IP and MAC configuration, active and standby router roles, timer settings, preemption configuration, multiple group implementation, VLAN-specific redundancy, monitoring and verification commands, integration with Layer 2 networks, troubleshooting failover scenarios, authentication for message security, operational tuning for fast convergence, load balancing using multiple groups, and interaction with routing protocols. Candidates should be able to configure HSRP, verify virtual gateway operation, troubleshoot failover and connectivity issues, optimize timers for rapid recovery, implement redundancy across multiple VLANs, maintain continuous network availability, secure protocol operation, and ensure consistent end-user connectivity. Mastery of HSRP enables network engineers to deploy resilient enterprise gateways, provide high availability, maintain seamless traffic flow, support critical applications, and manage failover scenarios effectively across complex network topologies.