EIGRP Interview Questions 1

Question 1

What is EIGRP?

Answer 1

EIGRP is an enhanced distance vector routing protocol that uses Diffused Update Algorithm (DUAL) to calculate the shortest path.

Question 2

What are the different packet types used by EIGRP?

Answer 2

The packet types used by EIGRP are:

1. Hello - Neighborship is discovered and maintained by Hello Packets.
2. Update - EIGRP uses Update messages to send routing information to neighbors. Update packets can be sent to a single neighbor using unicast or to a group of neighbors using multicast.
3. Query - Query packets Ask about routes. EIGRP will send queries if the network goes down.
4. Reply - Reply packets are used in response to the query packets. Reply packets are unicast to the originator of the query.
5. Acknowledgement - ACK packets are used to acknowledge the receipt of an update, query, and reply packet. Acknowledgment packets are Unicast.

Question 3

Explain what will happen if the packet is not acknowledged.

Answer 3

If a packet is not acknowledged, EIGRP will retransmit the packet to the non-responding neighbor as a unicast.

Question 4

Explain Split Horizon?

Answer 4

The Split Horizon feature prevents a route learned on one interface from being advertised back out of that same interface. It is used to prevent loop in EIGRP.

Question 5

Explain Stuck in Active?

Answer 5

The condition when a route becomes unreachable and not all queries for it are answered; adjacencies with unresponsive neighbors are reset