QUESTION: 9

The following figure shows the OSPF network of an enterprise and the OSPF configurations of R1.
Which of the following statements is false about the network?

R2 can access the server.
GE 0/0/1 of R1 cannot send OSPF packets.
The network segment to which GE 0/0/1 of R1 belongs cannot be advertised.
GE 0/0/1 of R1 cannot accept OSPF packets.

Answer(s): C

Explanation:

Silent Interface Explanation

The silent-interface command is used to prevent OSPF from sending or receiving OSPF packets on the specified interface (GE 0/0/1). This disables OSPF adjacency establishment and stops route advertisement for that interface.

Network Observations

Statement A: R2 can access the server.
This is correct, as the silent interface does not impact data traffic, only OSPF-related communication.

Statement B: GE 0/0/1 of R1 cannot send OSPF packets.
Correct due to the silent-interface configuration.

Statement C: The network segment to which GE 0/0/1 of R1 belongs cannot be advertised.

This is correct, as the silent interface prevents route advertisement.

Statement D: GE 0/0/1 of R1 cannot accept OSPF packets. Correct, as the silent interface configuration blocks packet reception.

HCIP-Datacom-Core Reference

OSPF interface command behavior is outlined in the configuration and lab examples sections.

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QUESTION: 10

On an OSPF network, if two routers with the same router ID run in different areas and one of the routers is an ASBR, LSA flapping occurs.

TRUE
FALSE

Answer(s): A

Explanation:

Understanding Router ID and Its Role in OSPF:
In OSPF, the Router ID uniquely identifies a router within the OSPF domain. If two routers are configured with the same Router ID, it can lead to issues such as LSA conflicts and flapping. This is because the Router ID is used as a key in OSPF operations, including LSA generation and database synchronization.

Reference:

HCIP-Datacom-Core Technology Training Material (OSPF Basics - Router ID and LSA Handling).

Scenario Details:

Different Areas: Even if the two routers belong to different areas, the Router ID remains globally significant in the OSPF domain. This means that any duplication of Router IDs will confuse OSPF mechanisms.

ASBR (Autonomous System Boundary Router): When one of the routers is an ASBR, it generates Type 4 and Type 5 LSAs to describe external routes. These LSAs use the Router ID as an identifier. If another router in the network has the same Router ID, conflicts occur during LSDB synchronization.

HCIP-Datacom Advanced Routing & Switching Technology (LSA Types and ASBR Operations).

Impact of Router ID Duplication:

LSA Flapping: The OSPF process receives conflicting LSAs from routers with the same Router ID. This results in continuous updates and withdrawals of these LSAs, causing flapping.

Routing Instability: LSA flapping leads to frequent recalculations of the OSPF shortest path tree (SPT), affecting overall network stability.

HCIE-Datacom V1.0 Training Material (OSPF Troubleshooting and Best Practices).

Conclusion:

The statement is TRUE. LSA flapping occurs when two routers in an OSPF network have the same Router ID, even if they are in different areas and one is an ASBR. This is due to the global significance of Router IDs in OSPF and the role they play in LSA generation and propagation.

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QUESTION: 11

On an OSPF network, routers learn routing information on the entire network by exchanging LSAs.
Which of the following values is the LS Age in the LSA header when an LSA is deleted?

1800s
3600s
1200s
600s

Answer(s): B

Explanation:

LSA Lifetime and Deletion

The LS Age field in the LSA header tracks the age of an LSA. When the LS Age reaches its maximum value (3600 seconds), the LSA is marked for deletion. This ensures old or stale LSAs are removed from the network to maintain accurate routing information.

HCIP-Datacom-Core Reference

Detailed explanation of LS Age behavior and LSA deletion processes can be found in the OSPF LSDB

and LSA sections.

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QUESTION: 12

DRAG DROP (Drag and Drop is not supported)

OSPF networks are classified into four types of networks by link layer protocol. Drag the following link layer protocols to the corresponding network types.(Token is reusable)

See Explanation for Answer.

Answer(s): A

Explanation:

Network Types and Corresponding Link Layer Protocols

Broadcast: Ethernet

Point-to-Point (P2P): PPP, HDLC

Point-to-Multipoint (P2MP): PPP

Non-Broadcast Multi-Access (NBMA): Frame Relay

OSPF Network Types:
OSPF classifies networks based on link layer protocols into the following types:

Broadcast: This type assumes that all routers on the network can communicate directly with one another using multicast or broadcast frames. Ethernet networks are typical examples.

Point-to-Point (P2P): This type is used for links that connect two routers directly. Common protocols include PPP (Point-to-Point Protocol) and HDLC.

Point-to-Multipoint (P2MP): This type simulates multiple point-to-point connections over a single physical network, often used in WAN scenarios where PPP is employed.

Non-Broadcast Multi-Access (NBMA): These networks connect multiple devices but lack native broadcast capability, such as Frame Relay.

Reference:

HCIP-Datacom-Core Technology Training Material (OSPF Network Types).

Explanation of Matches:

Broadcast - Ethernet: Ethernet supports broadcast and multicast communication, making it a suitable example of a broadcast OSPF network.

P2P - PPP, HDLC: Both PPP and HDLC are designed for direct communication between two nodes, fitting the P2P category.

P2MP - PPP: In WANs, PPP often operates in a point-to-multipoint configuration, simulating separate connections for each endpoint.

NBMA - Frame Relay: Frame Relay is a classic NBMA technology where direct communication between devices requires manual configuration, as there is no inherent broadcast capability.

Conclusion:
This classification ensures that OSPF operates efficiently over different network types by adapting neighbor discovery and LSA propagation mechanisms to the underlying link layer technology.

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