hardMultiple ChoiceObjective-mapped
300-410 Practice Question: A large enterprise network is experiencing…
A large enterprise network is experiencing intermittent reachability to a critical server (10.10.10.10). Router R1 has the following relevant configuration:
ip sla 1
icmp-echo 10.10.10.10 source-ip 192.168.1.1 frequency 10
ip sla schedule 1 life forever start-time now track 1 ip sla 1 reachability
delay down 5 up 5
ip route 0.0.0.0 0.0.0.0 192.168.1.2 track 1 Router R2 (the next-hop) shows:
show ip route | include 10.10.10.10
S 10.10.10.0/24 [1/0] via 10.0.0.1
What is the root cause?
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
✓
The IP SLA probe uses a source IP that is not reachable from the server, causing the probe to fail and the tracked route to be removed unnecessarily.
The IP SLA probes are sourced from 192.168.1.1, but the server 10.10.10.10 is in a different subnet. The return path from the server might not reach 192.168.1.1 due to route summarization or asymmetric routing. However, the key issue is that the tracked default route is removed when the probe fails, but the probe failure could be due to the server's response not being routed back correctly, not because the next-hop is unreachable. The correct answer is that the source IP of the probe is not routable from the server's perspective, causing false negatives.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The IP SLA probe uses a source IP that is not reachable from the server, causing the probe to fail and the tracked route to be removed unnecessarily.
Why this is correct
The source IP 192.168.1.1 may not be in the routing table of the server or intermediate routers, so echo replies never return, causing the track to go down.
- ✗
The frequency of the IP SLA is too high, causing the router to overload and drop the tracked route.
Why it's wrong here
A frequency of 10 seconds is standard and should not cause overload.
- ✗
The delay down 5 up 5 is too short, causing flapping of the tracked route.
Why it's wrong here
The delay values are reasonable and would not cause intermittent reachability by themselves.
- ✗
The server 10.10.10.10 is not responding to ICMP echo requests due to a firewall.
Why it's wrong here
While possible, the question indicates the server is critical and should respond; the root cause is more likely a routing issue with the source IP.
Visual reference
Quick reference
Symmetric Encryption Algorithm Comparison
| Algorithm | Key Size | Block Size | Status | Notes |
|---|---|---|---|---|
| AES-128 | 128-bit | 128-bit | Current standard | NIST approved; WPA3, TLS |
| AES-256 | 256-bit | 128-bit | Current standard | Preferred for sensitive / govt data |
| 3DES | 112-bit effective | 64-bit | Deprecated (2023) | Replaced by AES |
| DES | 56-bit | 64-bit | Broken | Cracked in < 24 h; never deploy |
| ChaCha20 | 256-bit | Stream cipher | Current | TLS 1.3, WireGuard |
Go deeper
Related to this question
Learn chapter
Introduction to ENARSI Exam and Network Fundamentals
Key term
IP SLA for Path Control
IP SLA for Path Control is a Cisco technology that uses active network measurements to dynamically influence routing decisions and redirect traffic along a preferred path when network conditions change.
Key term
BGP Route Aggregation
BGP Route Aggregation is a technique that combines multiple specific network routes into a single summary route to reduce the size of routing tables and improve network efficiency.
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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.