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Question 221

A large enterprise network uses OSPF and requires different parts of the network to maintain separate Link-State Databases while still exchanging routing information through a backbone. Which OSPF design feature provides this capability?

1. Autonomous System Boundary Router
2. OSPF Area
3. BGP Community
4. Route Target

Correct Answer: 2

Explanation

OSPF areas divide a large OSPF domain into smaller logical sections. Each area maintains its own Link-State Database, which helps reduce the amount of topology information that every router must maintain and process. The OSPF backbone, Area 0, provides connectivity between non-backbone areas. This hierarchical design improves scalability and can reduce SPF calculation overhead. An ASBR connects OSPF to another routing domain, while BGP communities and Route Targets are associated with BGP policy and VPN routing. Therefore, an OSPF Area is the appropriate design feature.

Question 222

A company wants to ensure that traffic destined for a critical application always follows a particular firewall before reaching the server network. Which technology can enforce this forwarding behavior?

1. PBR
2. ECMP
3. LACP
4. HSRP

Correct Answer: 1

Explanation

Policy-Based Routing allows traffic forwarding decisions to be based on defined policy conditions rather than relying solely on the destination routing table. An administrator can match specific source or destination addresses and then specify a particular next hop, such as a firewall. This can be useful when security inspection or application-specific traffic steering is required. ECMP distributes traffic across equal-cost paths, LACP aggregates physical links, and HSRP provides first-hop gateway redundancy. PBR is therefore suitable when traffic must deliberately pass through a particular security device.

Question 223

A service provider needs to support customers that use identical private IPv4 address ranges. Which MPLS VPN feature allows identical customer prefixes to coexist without being considered the same route?

1. Route Reflector
2. Route Distinguisher
3. Local Preference
4. BGP MED

Correct Answer: 2

Explanation

A Route Distinguisher makes otherwise identical customer prefixes unique within the provider’s VPN routing infrastructure. For example, two different customers can both use the same private prefix, but the RD creates a unique VPNv4 route representation for each customer. This allows overlapping address spaces to coexist on the provider network. Route Targets perform a different function by controlling VPN route import and export. Route Reflectors improve BGP scalability, while Local Preference and MED influence BGP path selection. Therefore, the Route Distinguisher provides the required route uniqueness.

Question 224

An organization wants to reduce the number of routes exchanged between two routing domains by representing several contiguous networks with a single prefix. What technique should be used?

1. Route summarization
2. Route redistribution
3. Policy-Based Routing
4. Load balancing

Correct Answer: 1

Explanation

Route summarization combines multiple more-specific prefixes into a single less-specific aggregate prefix. This reduces the number of routing entries that need to be advertised and maintained between routing domains. It can improve scalability and reduce the amount of routing information exchanged. However, the address allocation must support effective summarization, and the summary should not unintentionally attract traffic for unreachable destinations. Route redistribution exchanges routes between different routing protocols, PBR controls forwarding decisions, and load balancing distributes traffic. Route summarization directly addresses the requirement.

Question 225

A network architect wants to prevent a single physical link failure from disconnecting a server from its access switches. The server supports multiple network connections. Which design provides this redundancy?

1. Single-homed connection
2. Dual-homed connectivity
3. Static default route
4. Route summarization

Correct Answer: 2

Explanation

Dual-homed connectivity provides multiple physical connections between a server and the network infrastructure. Depending on the implementation, technologies such as NIC teaming, LACP, or multi-chassis link aggregation can provide redundancy and potentially active-active forwarding. If one physical connection fails, the server can continue communicating through the remaining connection. A single-homed design creates a single physical dependency. Static routes and route summarization do not provide physical connectivity redundancy. Therefore, dual-homed connectivity is the appropriate design approach for improving server access resilience.

Question 226

A company wants to use the same IP address to represent the nearest instance of a service from multiple network locations. Which addressing technique is commonly used?

1. Unicast
2. Broadcast
3. Anycast
4. Private VLAN

Correct Answer: 3

Explanation

Anycast allows multiple network locations to advertise the same IP address, with routing determining which instance is reached. This can provide geographically distributed service delivery and can direct users toward a topologically closer or preferred service instance. Anycast is commonly used for services such as DNS and distributed application infrastructure. Unicast identifies a single destination, broadcast sends traffic to all nodes within a broadcast domain, and private VLANs provide Layer 2 segmentation. Anycast is therefore the appropriate addressing technique for this requirement.

Question 227

A BGP router receives two routes to the same destination and the organization wants to prefer the path learned from its own internal routing policy over another path. Which attribute is generally considered early in the BGP decision process?

1. Local Preference
2. MED
3. Origin type
4. Router ID

Correct Answer: 1

Explanation

Local Preference is a key BGP attribute used to influence the preferred exit path within an autonomous system. A higher Local Preference is normally preferred during BGP path selection. Because it is propagated through iBGP, it can provide consistent outbound path selection across the AS. MED is generally used to communicate an inbound path preference to a neighboring AS, while origin type and Router ID are considered later in the selection process. Therefore, Local Preference is commonly used when an organization wants to establish its preferred internal BGP exit path.

Question 228

A data center uses VXLAN and needs to transport tenant Layer 2 segments across a Layer 3 IP underlay. Which component performs VXLAN encapsulation and decapsulation?

1. Route Reflector
2. VXLAN Tunnel Endpoint
3. DHCP Server
4. BGP Confederation

Correct Answer: 2

Explanation

A VXLAN Tunnel Endpoint, or VTEP, performs VXLAN encapsulation and decapsulation. When traffic leaves a local VXLAN segment, the VTEP encapsulates the original Ethernet frame inside UDP/IP and sends it across the Layer 3 underlay toward the remote VTEP. The receiving VTEP removes the VXLAN encapsulation and forwards the original frame into the destination segment. This architecture allows Layer 2 segments to be extended across a routed IP fabric without requiring the entire underlay to operate as Layer 2. The other options do not perform VXLAN tunnel termination.

Question 229

An enterprise has multiple routing protocols and needs to exchange routes between them. Which mechanism is required to move routing information from one routing protocol into another?

1. Route redistribution
2. ECMP
3. BFD
4. HSRP

Correct Answer: 1

Explanation

Route redistribution allows routes learned through one routing protocol or routing source to be introduced into another routing protocol. For example, an organization might redistribute selected OSPF routes into BGP or static routes into OSPF. Redistribution must be carefully controlled because differences in metrics, routing behavior, and administrative policy can create routing loops or suboptimal paths. Route maps, prefix lists, and filtering policies can be used to control redistributed routes. ECMP handles equal-cost forwarding, BFD detects failures, and HSRP provides gateway redundancy. Route redistribution directly satisfies the requirement.

Question 230

A network design requires rapid convergence after a link failure while avoiding unnecessary routing updates throughout the entire network. Which approach can help achieve this goal?

1. Appropriate hierarchical routing boundaries
2. One large Layer 2 broadcast domain
3. Removing redundancy
4. Using only static host routes

Correct Answer: 1

Explanation

Hierarchical routing boundaries can limit the scope of topology changes and reduce unnecessary routing information processing. Technologies such as OSPF areas allow networks to be divided into logical regions, reducing the amount of detailed topology information that must be maintained across the entire routing domain. Proper summarization and failure-domain design can further reduce the impact of failures. A large Layer 2 broadcast domain can increase the scope of certain failures, while removing redundancy reduces resilience. Static host routes are not a scalable convergence strategy. Hierarchical routing therefore supports controlled convergence.

Question 231

An organization wants to prevent BGP routes received from an external peer from becoming transit routes through its network. Which design principle should be applied?

1. Strict inbound and outbound route policy
2. Disable all BGP sessions
3. Increase Ethernet MTU
4. Enable STP on routed links

Correct Answer: 1

Explanation

Strict BGP routing policies can prevent an organization from unintentionally becoming a transit network. Inbound policies can control which routes are accepted from customers or peers, while outbound policies can ensure that only authorized prefixes are advertised to each neighbor. Prefix lists, route maps, communities, and AS-path policies can be combined to implement these controls. Simply disabling BGP would eliminate legitimate connectivity, while MTU and STP settings do not provide BGP route-policy control. Carefully designed inbound and outbound filtering is therefore essential for preventing unintended transit routing.

Question 232

A network architect is designing a campus network and wants to reduce the size of Layer 2 failure domains while allowing efficient inter-VLAN communication. Which architecture is appropriate?

1. Routed access design
2. Flat Layer 2 design
3. Single VLAN across the entire campus
4. Hub-and-spoke Layer 2 topology

Correct Answer: 1

Explanation

A routed access design uses Layer 3 connectivity closer to the network edge, reducing the size of Layer 2 domains. This can improve scalability, simplify failure isolation, and reduce dependence on spanning-tree convergence across large areas. Inter-VLAN communication can occur through routing rather than requiring large Layer 2 extensions. A flat Layer 2 design and a single VLAN across an entire campus increase the size of the broadcast and failure domains. A routed access architecture therefore provides a scalable approach for modern campus networks.

Question 233

A network has multiple links between switches and requires Layer 2 loop prevention. Which protocol determines which redundant Layer 2 paths should be blocked to create a loop-free topology?

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

Correct Answer: 3

Explanation

Spanning Tree Protocol prevents Layer 2 switching loops by logically blocking redundant paths while maintaining them as alternatives. STP elects a root bridge and calculates a loop-free topology based on path costs and bridge information. If an active path fails, a previously blocked path can become active depending on the STP implementation. BGP and OSPF are routing protocols used primarily at Layer 3, while BFD provides rapid failure detection. STP is therefore the technology designed to prevent Layer 2 loops in redundant switched networks.

Question 234

A company wants to ensure that a WAN application uses a low-latency link only when measured latency remains below a predefined threshold. Which network design capability supports this requirement?

1. Application-aware traffic steering
2. Static VLAN assignment
3. MAC address learning
4. Basic Ethernet switching

Correct Answer: 1

Explanation

Application-aware traffic steering can use real-time WAN performance measurements to select an appropriate path for application traffic. In an SD-WAN environment, policies can evaluate characteristics such as latency, jitter, packet loss, and availability. If a preferred link no longer satisfies the defined SLA, traffic can be redirected to another available path according to policy. Static VLAN assignment and MAC learning operate primarily at Layer 2 and do not evaluate WAN performance. Basic Ethernet switching also lacks application-aware WAN path selection. Traffic steering therefore provides the required functionality.

Question 235

A service provider wants to reduce the number of iBGP sessions required among many routers while maintaining full route distribution. Which BGP feature should be considered?

1. Route Reflector
2. NAT
3. HSRP
4. Anycast

Correct Answer: 1

Explanation

BGP Route Reflectors reduce the requirement for a full-mesh of iBGP sessions. Without route reflection, iBGP traditionally requires every router to establish sessions with every other iBGP router, creating significant scalability concerns as the network grows. A Route Reflector allows selected clients to exchange routes through the reflector, reducing the number of required sessions. Careful design is still necessary to avoid routing-policy problems and suboptimal paths. NAT, HSRP, and Anycast address different networking requirements and do not solve iBGP session scalability.

Question 236

A company wants to ensure that routes learned from a customer are never advertised to an unrelated external peer. Which BGP policy should be applied?

1. Outbound route filtering
2. Increasing the hold timer
3. Changing the router hostname
4. Enabling DHCP relay

Correct Answer: 1

Explanation

Outbound route filtering allows administrators to control which routes are advertised to a particular BGP neighbor. This is essential for preventing accidental route leaks and ensuring that customers, peers, and transit providers receive only the routes they are authorized to receive. Prefix lists, route maps, communities, and other policy mechanisms can be used to define the allowed advertisements. BGP timers do not determine which prefixes are advertised, while DHCP relay is unrelated to BGP routing policy. Outbound filtering is therefore the appropriate control.

Question 237

A network architect wants to distribute traffic across several equal-cost links while maintaining deterministic forwarding for individual flows. Which mechanism is commonly used?

1. Per-packet random forwarding
2. Hash-based ECMP
3. Route suppression
4. Broadcast flooding

Correct Answer: 2

Explanation

Hash-based ECMP can distribute flows across multiple equal-cost paths while maintaining consistent path selection for individual flows. A forwarding device typically calculates a hash using information such as source and destination addresses and transport-layer ports. The resulting value determines which available path is selected. This helps prevent packets belonging to the same flow from being reordered unnecessarily. Per-packet load balancing can cause packet reordering, while route suppression and broadcast flooding do not provide controlled equal-cost forwarding. Hash-based ECMP is therefore commonly used for scalable load distribution.

Question 238

An enterprise needs to carry multiple customer or tenant VLANs across a shared Layer 3 transport network while preserving tenant separation. Which technology combination is commonly used in modern data centers?

1. VXLAN with EVPN
2. STP with DHCP
3. HSRP with NAT
4. ARP with DNS

Correct Answer: 1

Explanation

VXLAN with EVPN is widely used to provide scalable tenant segmentation across a Layer 3 data center underlay. VXLAN creates virtual Layer 2 segments identified by VXLAN Network Identifiers, while EVPN provides a BGP-based control plane for advertising MAC and IP reachability. This combination supports large-scale multi-tenant environments and avoids extending traditional Layer 2 VLANs throughout the physical underlay. STP, DHCP, HSRP, NAT, ARP, and DNS can provide other functions, but they do not provide the complete scalable overlay architecture described in this scenario.

Question 239

A network administrator wants to make a BGP path less attractive for inbound traffic from a neighboring autonomous system by making the AS path appear longer. Which technique can be used?

1. AS-path prepending
2. Local Preference
3. Route Reflector
4. BFD

Correct Answer: 1

Explanation

AS-path prepending adds additional instances of the local autonomous system number to a BGP route’s AS-path attribute. Because BGP generally prefers a shorter AS path when other relevant attributes are equal, prepending can make a particular advertisement appear less attractive to neighboring autonomous systems. This technique is commonly used to influence inbound traffic. Local Preference primarily influences outbound path selection within an AS, Route Reflectors improve iBGP scalability, and BFD provides rapid failure detection. AS-path prepending is therefore the appropriate technique for this requirement.

Question 240

A network design requires secure separation between multiple business units while allowing selected services to be shared between them. Which approach provides controlled segmentation with explicit interconnection policies?

1. Unrestricted Layer 2 connectivity
2. VRF-based segmentation with controlled route leaking
3. One global routing table
4. Disabling routing between all networks

Correct Answer: 2

Explanation

VRF-based segmentation provides separate routing tables for different business units or tenants. Controlled route leaking can then allow only explicitly authorized prefixes or services to be shared between VRFs. This provides stronger separation than simply placing all networks into one global routing table while still supporting required inter-business-unit communication. Route leaking should be carefully controlled using routing policies, prefix filtering, and appropriate security controls. Unrestricted Layer 2 connectivity reduces segmentation, while completely disabling routing prevents legitimate shared services. VRF-based segmentation with controlled route leaking provides the required balance.