easyMultiple ChoiceObjective-mapped
200-901 Practice Question: Troubleshooting connectivity for a remote branch…
You are troubleshooting connectivity for a remote branch office. The branch router (BR) connects to the head office router (HQ) via a point-to-point T1 link. The HQ router is also connected to the internet via a separate interface. Users at the branch can access the internet but cannot reach servers at the head office (subnet 10.10.10.0/24). You run 'show ip route' on BR and see a default route pointing to HQ's IP address, but no specific route for 10.10.10.0/24. The HQ router has a connected route for that subnet. On HQ, you see that the interface towards BR is up/up, and you can ping the BR's interface IP. What is the most likely cause of the issue?
⚠ Common exam trap
Cisco often tests the concept that a default route on the branch router is sufficient for outbound traffic, but candidates forget that the head office router also needs a route back to the branch's subnet for return traffic to succeed.
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 HQ router does not have a route for the branch's local subnet.
The branch router (BR) has a default route pointing to the HQ router, which allows outbound traffic to the internet. However, for traffic from the branch to reach the HQ subnet (10.10.10.0/24), the HQ router must have a return route to the branch's local subnet. Without this specific route, the HQ router will drop packets destined for the branch because it does not know how to reach that network, even though the T1 link is up and the BR can ping the HQ interface. This is a classic asymmetric routing issue where the forward path works but the return path fails.
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 HQ router does not have a route for the branch's local subnet.
Why this is correct
Without a return route, traffic from branch to HQ can leave but replies are dropped.
- ✗
An ACL on the HQ router is blocking traffic from the branch subnet.
Why it's wrong here
There is no indication of ACL blocks; the issue is more fundamental.
- ✗
The default route on BR is not pointing to the correct next-hop.
Why it's wrong here
If internet works, the default route is correct for outgoing traffic.
- ✗
The T1 link is experiencing errors causing packet loss.
Why it's wrong here
Internet connectivity works, so the link is functional.
Visual reference
Quick reference
Asymmetric Encryption Algorithm Comparison
| Algorithm | Key Exchange | Signatures | Equivalent Security Key | Notes |
|---|---|---|---|---|
| RSA-3072 | Yes | Yes | 128-bit | Widely deployed; slow for bulk data |
| ECDSA P-256 | No | Yes | 128-bit | Fast signatures; standard TLS certs |
| ECDH / ECDHE | Yes | No | 128-bit | Perfect forward secrecy in TLS 1.3 |
| DH / DHE | Yes | No | 128-bit (3072-bit key) | Replaced by ECDHE in modern TLS |
| Ed25519 | No | Yes | ~128-bit | SSH keys, modern PKI |
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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