EIGRP Reply Packet Characteristics | Generated by AI
Question: Which EIGRP packet is sent as a unicast and requires acknowledgment?
A) Hello
B) Update
C) Query
D) Reply
Answer:
D) Reply
In EIGRP, the Reply packet is always sent as a unicast to the router that originated the Query. Like Update and Query packets, Reply packets are transmitted reliably via EIGRP’s Reliable Transport Protocol (RTP), which requires an explicit acknowledgment (ACK) from the recipient.
- Hello packets are multicast (or unicast in specific cases like static neighbors) and unreliable—no acknowledgment required.
- Update packets can be multicast or unicast but are reliable when sent.
- Query packets are typically multicast (retransmitted as unicast if needed) and reliable.
- Only Reply consistently matches both criteria: always unicast and always requires acknowledgment.
References:
- https://www.computernetworkingnotes.com/ccna-study-guide/eigrp-packet-types-and-rtp-protocol.html
- https://www.geeksforgeeks.org/computer-networks/types-of-eigrp-packet-in-computer-network/
- https://ipcisco.com/lesson/eigrp-packet-types-and-neighbourship-ccnp/
- https://www.cisco.com/c/en/us/support/docs/ip/enhanced-interior-gateway-routing-protocol-eigrp/13669-1.html