hardMultiple Select
300-410 Practice Question: Which TWO statements about BFD echo mode are…
Which TWO statements about BFD echo mode are true? (Choose TWO.)
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
✓
Echo packets are generated by the sending router and forwarded back by the remote router.
Option A is correct because in BFD echo mode the local (sending) router originates echo packets with its own address as the destination, and the remote router simply loops them back along the reverse path without processing them as BFD control packets. Option B is correct because the remote router only has to forward the echoed packet at the data plane, so it does not run BFD state-machine processing, which reduces the load on its control plane. Option C is incorrect because echo mode still uses a single BFD session; the echo function is an addition to that session, not a separate per-direction session. Option D is incorrect because echo mode actually reduces the number of BFD control packets exchanged, since the echo packets replace frequent control-packet transmission. Option E is incorrect because BFD echo mode is not enabled by default on interfaces; it must be explicitly configured.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Echo packets are generated by the sending router and forwarded back by the remote router.
Why this is correct
In echo mode the local router transmits echo packets that the remote router simply reflects back along the same path, without the remote system maintaining its own BFD session state. This differs from asynchronous mode, where both routers independently send control packets to each other.
- ✓
Echo mode reduces the processing load on the remote router's control plane.
Why this is correct
Echo mode offloads session maintenance to the sending router, so the remote device merely loops packets back and needs no BFD timer processing or state machine. This reduces demand on the remote router's control plane compared with asynchronous mode, where both ends run timers.
- ✗
Echo mode requires a separate BFD session for each direction.
Why it's wrong here
Echo mode uses a single BFD session, with the local system transmitting echo packets that the neighbour reflects back, so no per-direction session exists. It is tempting because asynchronous mode maintains independent transmit and receive intervals, and separate sessions per direction would be correct for that mode instead.
- ✗
Echo mode increases the number of BFD control packets sent between routers.
Why it's wrong here
Echo mode suppresses periodic control packets once the session is up, so it reduces, not increases, control traffic. It is tempting because echo packets are still generated by the local system, but they are data-plane probes reflected by the neighbour, not BFD control packets exchanged between routers.
- ✗
Echo mode is enabled by default on all interfaces.
Why it's wrong here
Echo mode is disabled by default and must be explicitly configured on the interface; it is not universally active. It is tempting because echo packets are generated locally by the forwarding engine, and enabling it globally would be the correct approach only where every interface runs a BFD neighbour needing reduced control-plane load.
Go deeper
Related to this question
About these practice questions
Courseiva writes every 300-410 question from scratch — 1,401 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.