easyMultiple Choice
300-410 Practice Question: Which EIGRP packet type is used to confirm…
Which EIGRP packet type is used to confirm receipt of a reliable update?
⚠ Common exam trap
300-410 often tests the confusion between Hello and ACK, since ACK is a Hello with a flag, and candidates may think ACK is a separate packet type or that Hello acknowledges updates.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
ACK
In EIGRP, reliable updates (Update, Query, Reply) require acknowledgment. The ACK packet is a Hello packet with the Acknowledgment field set, and it is used to confirm receipt of a reliable update. It is not a separate packet type but a function of the Hello packet.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Hello
Why it's wrong here
Hello packets serve neighbour discovery and keepalive functions, not reliable transport confirmation. Reliable EIGRP updates require an ACK packet to acknowledge receipt; Hello packets lack the sequence-number tracking mechanism that ACKs use to confirm delivery. The temptation arises because Hello packets are the most frequent EIGRP packet type and are involved in forming adjacencies, so one might assume they handle all control-plane acknowledgements. In a scenario requiring only neighbour maintenance or dead-interval detection, Hello would be the correct choice.
- ✓
ACK
Why this is correct
EIGRP uses the ACK packet to acknowledge reliable packets such as Updates, Queries and Replies. It is a hello packet with the acknowledgement field populated and the init flag clear, sent as a unicast to confirm receipt without requiring further acknowledgement.
- ✗
Update
Why it's wrong here
Update packets carry routing information and are sent reliably, but they do not acknowledge anything; acknowledgement is a separate function. Update tempts because it is the reliable packet type, yet reliability here means the sender expects confirmation, not that the packet provides it. Hello and Query serve other purposes.
- ✗
Reply
Why it's wrong here
Reply packets answer specific queries and are sent unreliably; they carry no acknowledgement field for confirming receipt of an update. Reply tempts because it is a response packet, suggesting confirmation, but EIGRP acknowledgement is a distinct packet type. Query and Update handle discovery and route propagation.
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
Go deeper
Related to this question
About these practice questions
One of 1,401 original 300-410 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 300-410 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 300-410 exam.