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Question 61

Which EIGRP feature prevents a router from accepting an update for a route from the same interface through which that route was learned?

1. Route summarization
2. Split horizon
3. Stub routing
4. Feasibility condition

Correct Answer: 2

Explanation

EIGRP uses split horizon to prevent routing loops by preventing a router from advertising a route back through the interface from which that route was originally learned. This behavior is particularly useful on networks where routing information could otherwise travel back toward the router that originally advertised it. Split horizon reduces unnecessary routing updates and helps maintain stable routing behavior. However, there are certain network designs, such as some hub-and-spoke Frame Relay environments, where split horizon may need special consideration. Administrators should understand how the feature operates on different interface types before modifying it, because disabling split horizon can affect routing stability.

Question 62

Which BGP attribute is commonly manipulated using AS-path prepending to influence inbound traffic?

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

Correct Answer: 3

Explanation

AS-path prepending is a BGP traffic-engineering technique that adds additional copies of an autonomous system number to the AS Path when advertising a route. This makes the advertised path appear longer to external BGP networks. Since BGP generally prefers a shorter AS Path when higher-priority attributes are equal, prepending can influence neighboring networks to select another available path. The technique primarily affects inbound traffic because it changes how external networks evaluate routes toward the advertising autonomous system. AS-path prepending should be applied carefully because its effectiveness depends on the routing policies and path-selection behavior of neighboring networks.

Question 63

Which OSPF LSA type carries information about external destinations redistributed into OSPF?

1. Type 5
2. Type 2
3. Type 3
4. Type 1

Correct Answer: 1

Explanation

OSPF Type 5 LSAs, known as AS External LSAs, carry information about routes that originate outside the OSPF autonomous system and have been redistributed into OSPF. An Autonomous System Boundary Router generates these LSAs when external routes are introduced. Type 5 LSAs normally flood throughout the OSPF autonomous system, although special area types can restrict or modify their propagation. Type 1 LSAs describe routers, Type 2 LSAs describe multiaccess networks, and Type 3 LSAs advertise inter-area networks. Understanding Type 5 LSAs is important when troubleshooting route redistribution and determining how external prefixes are propagated through an OSPF environment.

Question 64

Which EIGRP command displays interface-specific EIGRP information?

1. show ip eigrp topology
2. show ip eigrp interfaces
3. show ip route eigrp
4. show ip eigrp neighbors

Correct Answer: 2

Explanation

The show ip eigrp interfaces command displays information about interfaces participating in EIGRP. Depending on the IOS version and command options, the output can include interface status, autonomous system information, peer counts, hello intervals, hold times, packet statistics, and other operational details. This command is useful when troubleshooting why an interface is not forming EIGRP neighbor relationships or why routing updates are not behaving as expected. The neighbors command focuses on established peers, while the topology command provides route information. Checking interface-specific information can help identify configuration mismatches, passive-interface settings, timers, authentication issues, or other EIGRP operational problems.

Question 65

Which BGP attribute is considered before AS Path in the standard Cisco best-path selection process?

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

Correct Answer: 3

Explanation

Local Preference is considered before AS Path during the standard Cisco BGP best-path selection process. BGP generally prefers the path with the highest Local Preference value among otherwise eligible routes. If the Local Preference values are equal, subsequent attributes such as locally originated routes, AS Path length, Origin, and MED may be considered. This ordering allows administrators to use Local Preference as a strong policy mechanism for selecting preferred outbound paths within an autonomous system. Understanding the order of BGP attributes is important because changing a lower-priority attribute may have no effect when a higher-priority attribute has already caused one route to be selected.

Question 66

Which OSPF command displays the process ID, router ID, areas, and other general OSPF information?

1. show ip ospf
2. show ip ospf database
3. show ip ospf neighbor
4. show ip route ospf

Correct Answer: 1

Explanation

The show ip ospf command displays general information about the OSPF process running on a router. The output can include the process ID, router ID, area information, number of interfaces, SPF statistics, timers, and other operational details. This command is useful as a starting point when troubleshooting OSPF because it provides an overview of how the local OSPF process is configured and operating. The database command focuses on LSAs, the neighbor command focuses on adjacency relationships, and the routing command shows installed OSPF routes. Reviewing general OSPF process information can help identify configuration problems before examining more specific issues.

Question 67

Which EIGRP packet type is used to advertise routing information to neighbors?

1. Query
2. Update
3. Reply
4. Hello

Correct Answer: 2

Explanation

EIGRP Update packets are used to advertise routing information to neighboring routers. Updates can contain information about new routes, changes to existing routes, or route withdrawals. EIGRP uses reliable delivery for important routing updates and can send them as unicast or multicast depending on the situation. Hello packets are primarily used for neighbor discovery and maintenance, Query packets request alternative route information, and Reply packets respond to Queries. Understanding the purpose of each EIGRP packet type helps administrators troubleshoot routing convergence and neighbor communication. Update packets are especially important when verifying whether a router is actually advertising expected network prefixes.

Question 68

Which BGP attribute is commonly used to prefer a route that was originated locally?

1. Local Preference
2. Origin
3. Weight
4. MED

Correct Answer: 3

Explanation

Weight is a Cisco-specific BGP attribute that can be used to prefer a locally selected path on an individual router. Routes originated locally can receive a higher Weight depending on how BGP is configured, and the router prefers the path with the highest Weight. Because Weight is local to the Cisco router and is not advertised to BGP peers, its effect does not automatically extend throughout the autonomous system. Local Preference is generally used when administrators need a policy that affects multiple routers through iBGP. Understanding the difference between local Weight and propagated Local Preference is important when designing BGP traffic-engineering policies.

Question 69

Which OSPF LSA type describes the network segment represented by a Designated Router?

1. Type 2
2. Type 4
3. Type 5
4. Type 3

Correct Answer: 1

Explanation

OSPF Type 2 LSAs are Network LSAs generated by the Designated Router on broadcast and certain other multiaccess network segments. The Type 2 LSA identifies the network segment and lists the routers connected to that segment. This allows OSPF routers to represent the shared network efficiently in the link-state database without requiring every router to form a full adjacency with every other router. Type 1 LSAs describe individual routers, Type 3 LSAs advertise networks between areas, and Type 4 LSAs provide information about ASBR locations. Type 2 LSAs therefore play an important role in OSPF operation on multiaccess networks.

Question 70

Which EIGRP administrative distance is normally assigned to internal EIGRP routes?

1. 90
2. 110
3. 170
4. 120

Correct Answer: 1

Explanation

Cisco routers normally assign an administrative distance of 90 to internal EIGRP routes. Administrative distance is used to determine the trustworthiness of routing information when multiple routing protocols provide routes to the same destination. A lower administrative distance is preferred. External EIGRP routes normally have an administrative distance of 170 because they were learned through redistribution from another routing source. OSPF normally uses 110, while RIP normally uses 120. Understanding administrative distance is important when multiple routing protocols operate simultaneously because it helps explain which route is installed in the main IP routing table.

Question 71

Which BGP attribute is generally preferred when its value is lower during path selection?

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

Correct Answer: 3

Explanation

The Multi-Exit Discriminator, or MED, is generally preferred when its value is lower during BGP path selection. MED is used to provide a neighboring autonomous system with information about which entry point into the advertising autonomous system may be preferred when multiple links are available. MED comparison behavior can depend on configuration, including whether paths are received from the same neighboring autonomous system. Unlike Local Preference, which uses a higher value as the preferred choice, MED normally favors a lower value. Administrators should understand the BGP topology and comparison rules before using MED because neighboring networks can apply their own routing policies.

Question 72

Which OSPF feature can reduce the size of the routing table by advertising a summarized prefix?

1. LSA flooding
2. Route summarization
3. DR election
4. SPF calculation

Correct Answer: 2

Explanation

OSPF route summarization allows multiple specific prefixes to be represented by a larger summary prefix. This can reduce the number of routes that need to be advertised between areas and can simplify routing tables. Inter-area summarization is typically performed by an ABR using an area range configuration. External route summarization can also be performed by an ASBR for redistributed routes. Proper summarization can reduce routing overhead and limit the propagation of individual topology changes. However, administrators must carefully select summary ranges because an overly broad summary can cause traffic to be directed toward a router even when the specific destination is unavailable.

Question 73

Which EIGRP feature can provide a backup route without requiring a new route calculation after the primary route fails?

1. Split horizon
2. Route redistribution
3. Feasible successor
4. Route filtering

Correct Answer: 3

Explanation

An EIGRP feasible successor provides a precomputed backup route that satisfies the feasibility condition. When the current successor becomes unavailable, EIGRP can immediately install the feasible successor without first performing the complete route discovery process. This contributes to EIGRP’s rapid convergence behavior. The feasibility condition ensures that the alternate path is considered loop-free based on the reported distance received from the neighbor. Not every alternate route qualifies as a feasible successor. If no feasible successor exists after a primary route failure, EIGRP may need to query neighbors and perform additional DUAL processing before selecting another path.

Question 74

Which BGP attribute is used to identify the BGP speaker within an autonomous system?

1. Router ID
2. MED
3. Origin
4. Weight

Correct Answer: 1

Explanation

The BGP Router ID uniquely identifies a BGP speaker within the BGP process. It is a 32-bit value commonly represented in IPv4 address format. When configured manually, the router uses the specified BGP router ID. If it is not manually configured, Cisco IOS can select an appropriate address based on the router’s interfaces and configuration. The Router ID is important for BGP operation and can also be involved in the final stages of best-path selection when multiple routes remain otherwise equivalent. It should be configured consistently and predictably, particularly in environments where stable routing behavior and clear troubleshooting information are required.

Question 75

Which OSPF area is designed to reduce the amount of external routing information by blocking Type 5 LSAs?

1. Standard area
2. Stub area
3. Backbone area
4. Transit area

Correct Answer: 2

Explanation

An OSPF stub area is designed to reduce external routing information by preventing Type 5 LSAs from entering the area. Instead of learning individual external routes, routers inside the stub area can use a default route generated by the ABR to reach destinations outside the area. This reduces the size of the link-state database and simplifies routing information for routers that do not need detailed external routes. Stub areas have specific restrictions and cannot contain an internal ASBR that redistributes external routes in the normal way. For networks with limited external routing requirements, this design can reduce routing overhead and simplify OSPF operation.

Question 76

Which command displays the EIGRP topology information for a specific destination?

1. show ip eigrp topology all-links
2. show ip route
3. show ip eigrp interfaces
4. show ip eigrp neighbors

Correct Answer: 1

Explanation

The show ip eigrp topology all-links command displays detailed EIGRP topology information, including routes that may not currently be installed as successors. This is useful when investigating why a particular path was selected or why an alternate route did not become a feasible successor. The topology information can include feasible distance, reported distance, successor information, and other path details. The routing table only shows routes selected for forwarding, while the neighbor command focuses on EIGRP peer relationships. Examining all available links can therefore provide additional information during EIGRP troubleshooting, especially when analyzing DUAL decisions and alternate path eligibility.

Question 77

Which BGP attribute can be used to control outbound traffic by assigning different preferences to routes received from different providers?

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

Correct Answer: 2

Explanation

Local Preference is commonly used to control outbound traffic when an autonomous system has multiple external providers or multiple paths to the same destination. Administrators can assign different Local Preference values to routes received from different BGP neighbors. The router and its internal BGP peers will generally prefer the path with the highest Local Preference. This allows an organization to establish a preferred Internet or external exit point while retaining another connection as an alternative. Local Preference is propagated through iBGP, making it more suitable for autonomous-system-wide outbound policy than Weight, which affects only the local router.

Question 78

Which OSPF command can be used to verify the configured OSPF router ID?

1. show ip ospf
2. show ip ospf database
3. show ip ospf neighbor
4. show ip route ospf

Correct Answer: 1

Explanation

The show ip ospf command displays general information about the local OSPF process, including the configured or selected OSPF router ID. The router ID uniquely identifies an OSPF router within the OSPF domain and is used in neighbor relationships and link-state information. If a router ID is manually configured, it provides predictable identification. Otherwise, Cisco IOS can select one based on available addresses according to the OSPF router-ID selection process. The database and neighbor commands provide different information, while the routing command focuses on installed routes. Checking the router ID can help troubleshoot unexpected OSPF neighbor relationships and topology information.

Question 79

Which EIGRP administrative distance is normally assigned to external EIGRP routes?

1. 90
2. 110
3. 170
4. 115

Correct Answer: 3

Explanation

External EIGRP routes normally have an administrative distance of 170 on Cisco routers. These routes are learned through EIGRP redistribution from another routing protocol or routing source. Internal EIGRP routes normally have an administrative distance of 90, making them more preferred when competing with external EIGRP routes. Administrative distance determines which routing source is trusted when multiple protocols provide routes to the same destination. The higher value assigned to external EIGRP reflects the fact that the route originated outside the native EIGRP routing domain. Understanding these values helps explain route selection when multiple routing protocols are configured on the same router.

Question 80

Which BGP feature allows a router to advertise a default route to a BGP neighbor?

1. Route reflector
2. BGP community
3. Default-information originate
4. Network 0.0.0.0

Correct Answer: 4

Explanation

A BGP router can advertise a default route using a network statement for 0.0.0.0/0 when the corresponding route exists in the routing table and the BGP configuration permits its advertisement. The command network 0.0.0.0 mask 0.0.0.0 can be used to originate the default route into BGP under appropriate conditions. Another commonly used method is the neighbor default-originate command, which can advertise a default route directly to a specified BGP neighbor. Administrators should distinguish BGP default-route advertisement from IGP default-information originate because they are separate routing mechanisms. Proper configuration ensures neighbors receive the intended default path.