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Question 1

Which protocol is commonly used to dynamically exchange routing information between autonomous systems?

1. OSPF
2. EIGRP
3. BGP
4. STP

Correct Answer: 3

Explanation

Border Gateway Protocol (BGP) is the primary routing protocol used to exchange routing information between autonomous systems. Unlike OSPF and EIGRP, which are commonly used within an organization, BGP is designed for interdomain routing. BGP uses attributes such as AS path, local preference, MED, and weight to influence route selection. It establishes neighbor relationships using TCP port 179. Network engineers use BGP extensively for Internet connectivity, service-provider networks, and environments requiring advanced routing policy control between autonomous systems.

Question 2

Which protocol prevents Layer 2 switching loops in a redundant Ethernet network?

1. STP
2. FTP
3. NTP
4. SNMP

Correct Answer: 1

Explanation

Spanning Tree Protocol (STP) prevents Layer 2 loops by logically blocking redundant paths while maintaining them as backups. Without loop prevention, redundant Ethernet connections can cause broadcast storms, duplicate frames, and MAC address instability. STP elects a root bridge and calculates the best paths toward that root. When a topology change occurs, STP can adjust forwarding decisions. Modern Cisco networks may use Rapid PVST+ or Multiple Spanning Tree Protocol to provide faster convergence and more scalable Layer 2 loop prevention.

Question 3

Which OSPF packet type is used to discover and maintain neighbor relationships?

1. Link-State Update
2. Database Description
3. Link-State Acknowledgment
4. Hello

Correct Answer: 4

Explanation

OSPF Hello packets are used to discover neighbors and maintain OSPF neighbor relationships. They are transmitted periodically and contain information such as the router ID, area ID, hello and dead intervals, network mask, and authentication information when configured. Neighbor routers must have compatible parameters before forming an adjacency. Other OSPF packet types serve different purposes: Database Description packets summarize databases, Link-State Updates carry LSAs, and Link-State Acknowledgments confirm receipt of LSAs. Hello packets are therefore fundamental to OSPF neighbor discovery and maintenance.

Question 4

Which technology allows multiple VLANs to traverse a single Ethernet link between switches?

1. EtherChannel
2. 802.1Q trunking
3. Port security
4. DHCP snooping

Correct Answer: 2

Explanation

IEEE 802.1Q trunking allows multiple VLANs to traverse a single physical Ethernet connection. The switch adds VLAN identification information to Ethernet frames so the receiving switch can determine which VLAN each frame belongs to. Trunk links are commonly used between switches, routers, firewalls, and other network devices that need connectivity to multiple VLANs. EtherChannel combines multiple physical links for increased bandwidth and redundancy, but it does not itself provide VLAN tagging. Proper trunk configuration is essential for maintaining VLAN connectivity across switches.

Question 5

A network administrator wants to automatically assign IPv4 addresses to client devices. Which service should be configured?

1. DNS
2. NTP
3. DHCP
4. SNMP

Correct Answer: 3

Explanation

Dynamic Host Configuration Protocol (DHCP) automatically provides IP configuration information to client devices. A DHCP server can assign an IP address, subnet mask, default gateway, DNS servers, and other parameters. This eliminates the need to manually configure every endpoint and reduces configuration errors. DHCP uses UDP ports 67 and 68 for IPv4 communication. In larger networks, DHCP relay functionality can forward client requests between different network segments when the DHCP server is located outside the local broadcast domain.

Question 6

Which Cisco technology bundles multiple physical interfaces into a single logical link?

1. HSRP
2. GRE
3. VRF
4. EtherChannel

Correct Answer: 4

Explanation

EtherChannel combines multiple physical Ethernet interfaces into one logical interface called a Port-Channel. This provides increased bandwidth and redundancy while simplifying management because the bundled links are treated as a single logical connection. EtherChannel can use protocols such as LACP or PAgP, depending on the configuration and platform. LACP is based on the IEEE 802.3ad standard and is widely used for dynamic link aggregation. Properly matching parameters such as speed, duplex, VLAN configuration, and negotiation settings is important for successful EtherChannel formation.

Question 7

Which BGP attribute is commonly used to prefer an exit path within an autonomous system?

1. Local Preference
2. AS Path
3. Origin
4. MED

Correct Answer: 1

Explanation

Local Preference is a BGP attribute used within an autonomous system to influence which exit path should be preferred for outbound traffic. A higher local preference value is preferred. Because the attribute is propagated through iBGP within the autonomous system, it is commonly used to establish an organization’s preferred Internet exit point. AS Path length is another important BGP selection factor, while MED can influence how neighboring autonomous systems prefer inbound paths. Understanding BGP attributes is essential for implementing predictable routing policies.

Question 8

Which protocol is commonly used to synchronize time across network devices?

1. SSH
2. NTP
3. TFTP
4. Syslog

Correct Answer: 2

Explanation

Network Time Protocol (NTP) synchronizes clocks across network devices and systems. Accurate time is important for troubleshooting, security investigations, logging, authentication, and event correlation. Cisco devices can operate as NTP clients, servers, or peers depending on the network design. Centralized time synchronization ensures that timestamps in logs and monitoring systems can be compared accurately. NTP normally uses UDP port 123. Without consistent time settings, administrators may have difficulty determining the sequence of network events or correlating security incidents across multiple devices.

Question 9

Which protocol provides secure remote CLI access to a Cisco device?

1. Telnet
2. HTTP
3. SSH
4. TFTP

Correct Answer: 3

Explanation

Secure Shell (SSH) provides encrypted remote command-line access to Cisco devices. Unlike Telnet, SSH protects credentials and session information by encrypting communication between the administrator and the device. Cisco IOS devices require appropriate configuration, including hostname, domain name, user credentials or authentication mechanisms, and RSA keys for typical SSH operation. SSH commonly uses TCP port 22. Secure remote management is an important network-security practice because unencrypted management protocols can expose sensitive information to attackers monitoring network traffic.

Question 10

Which mechanism allows multiple private IPv4 addresses to share a single public IPv4 address?

1. Static routing
2. PAT
3. OSPF
4. VRRP

Correct Answer: 2

Explanation

Port Address Translation (PAT), also called NAT overload, allows multiple private IPv4 addresses to share a single public IPv4 address by using different source port numbers. The translation device tracks sessions so return traffic can be mapped back to the correct internal host. PAT is widely used when an organization has many private devices but a limited number of public IPv4 addresses. Static routing determines packet paths, OSPF exchanges routing information, and VRRP provides gateway redundancy rather than address translation.

Question 11

Which virtualization technology creates separate routing tables on the same physical router?

1. VLAN
2. VXLAN
3. VRF
4. EtherChannel

Correct Answer: 3

Explanation

Virtual Routing and Forwarding (VRF) allows a single physical router or Layer 3 device to maintain multiple independent routing tables. Each VRF can contain separate routes and forwarding information, allowing overlapping IP address spaces to coexist without directly interfering with one another. VRFs are commonly used for customer separation, network segmentation, and service-provider environments. VLANs separate Layer 2 broadcast domains, while VXLAN provides network virtualization and Layer 2 extension over Layer 3 infrastructure. EtherChannel combines physical links into a logical interface.

Question 12

A network engineer needs to identify the path packets take toward a remote destination. Which tool is most appropriate?

1. traceroute
2. ping
3. nslookup
4. show interfaces

Correct Answer: 1

Explanation

Traceroute is used to identify the sequence of Layer 3 hops between a source and destination. It helps network engineers determine where latency, packet loss, or routing problems may occur along a path. The tool works by sending packets with progressively increasing TTL values and analyzing the responses from intermediate routers. Ping primarily tests reachability and round-trip response time, while nslookup is used for DNS queries. Interface commands provide information about local interfaces but do not directly reveal the complete path toward a remote destination.

Question 13

Which Cisco security feature helps prevent unauthorized DHCP servers from responding to clients?

1. Dynamic ARP Inspection
2. IP Source Guard
3. DHCP snooping
4. Port security

Correct Answer: 3

Explanation

DHCP snooping helps protect a Layer 2 network from unauthorized or rogue DHCP servers. The switch classifies ports as trusted or untrusted. DHCP server responses are normally allowed only through trusted interfaces, while client-facing interfaces are treated as untrusted. DHCP snooping can also build a binding database containing information such as MAC addresses, IP addresses, VLANs, and interfaces. This database can support other security features, including Dynamic ARP Inspection and IP Source Guard, making DHCP snooping an important foundation for Layer 2 security.

Question 14

Which protocol is used by Cisco devices to discover directly connected Cisco neighbors?

1. CDP
2. BGP
3. HSRP
4. RADIUS

Correct Answer: 1

Explanation

Cisco Discovery Protocol (CDP) is a Cisco proprietary Layer 2 discovery protocol that allows Cisco devices to learn information about directly connected Cisco neighbors. Information can include device identity, platform, interface, and address details. CDP is useful for network discovery and troubleshooting because administrators can identify which devices are connected to specific interfaces. It should be used carefully in security-sensitive environments because discovered information can potentially reveal network details. LLDP is an industry-standard alternative that supports multivendor network environments.

Question 15

Which first-hop redundancy protocol is commonly used to provide a virtual default gateway for hosts?

1. FTP
2. HSRP
3. OSPF
4. SNMP

Correct Answer: 2

Explanation

Hot Standby Router Protocol (HSRP) provides first-hop redundancy by allowing multiple routers to present a shared virtual IP address to hosts. One router operates as the active router while another can assume the role if the active router becomes unavailable. End devices use the virtual address as their default gateway, so gateway redundancy can occur without changing host configuration. HSRP is particularly useful in networks where uninterrupted default-gateway availability is important. Other technologies, such as VRRP, can provide similar first-hop redundancy using different standards.

Question 16

Which QoS mechanism is primarily used to classify and mark traffic?

1. Policing
2. Shaping
3. Classification and marking
4. Congestion avoidance

Correct Answer: 3

Explanation

Classification and marking identify traffic and assign markings that can be used later for appropriate quality-of-service treatment. For example, traffic may be classified according to application, protocol, source, destination, or other characteristics and then marked using DSCP or CoS values. Subsequent QoS mechanisms can use these markings to determine how traffic should be queued, prioritized, shaped, or policed. Policing controls traffic rates by enforcing limits, while shaping buffers traffic to smooth transmission. Classification and marking therefore provide an important foundation for end-to-end QoS policies.

Question 17

Which REST API HTTP method is generally used to retrieve information from a resource?

1. POST
2. DELETE
3. PUT
4. GET

Correct Answer: 4

Explanation

The HTTP GET method is generally used to retrieve information from a REST API resource without requesting a modification to that resource. In network automation, GET requests can retrieve information such as device configuration, interface status, or operational data. POST is commonly used to create or submit resources, PUT is generally used to create or replace a resource, and DELETE removes a resource. Understanding HTTP methods is important when working with REST-based network management and automation systems.

Question 18

What is the primary purpose of VXLAN in modern data center networks?

1. Provide encrypted remote access
2. Extend Layer 2 networks over a Layer 3 underlay
3. Replace DNS services
4. Synchronize device clocks

Correct Answer: 2

Explanation

Virtual Extensible LAN (VXLAN) provides network virtualization by encapsulating Layer 2 Ethernet frames within Layer 3 UDP packets. This allows Layer 2 segments to be extended across a routed Layer 3 underlay while supporting a much larger number of logical network segments than traditional VLANs. VXLAN is commonly deployed in modern data center architectures, particularly with spine-leaf designs. It separates the logical overlay from the physical underlay, providing greater scalability and flexibility. VXLAN commonly uses UDP port 4789 for encapsulated traffic.

Question 19

Which protocol is commonly used to securely authenticate network administrators against a centralized authentication server?

1. RADIUS
2. TFTP
3. FTP
4. CDP

Correct Answer: 1

Explanation

RADIUS is a centralized authentication, authorization, and accounting protocol commonly used for controlling administrative or network access. Organizations can use a central RADIUS server so that users do not need separate locally configured credentials on every network device. RADIUS supports centralized policy management and is widely used with network access services and device administration. TACACS+ is another protocol commonly used for centralized device administration, particularly in Cisco environments. Centralized authentication improves administrative control, consistency, and the ability to manage user access across many devices.

Question 20

A network engineer wants to automate repetitive configuration tasks across many Cisco devices. Which approach is most appropriate?

1. Configure every device manually.
2. Use network automation tools and APIs.
3. Disable device logging.
4. Increase interface bandwidth.

Correct Answer: 2

Explanation

Network automation tools and APIs allow engineers to perform repetitive configuration and operational tasks consistently across multiple devices. Automation can reduce manual errors, improve deployment speed, and make configuration changes more repeatable. Technologies such as REST APIs, Python, Ansible, and model-driven programmability can be used depending on the environment and requirements. Manual configuration may be practical for a small number of devices but becomes inefficient and error-prone at scale. Effective automation should also include appropriate validation, testing, security controls, and change-management practices.