CCNA Network Services and Security Practice Question
A technician is troubleshooting an issue where internal hosts can successfully ping internet addresses but cannot establish HTTP sessions. The router is configured with PAT (overload) and uses an access list to define the inside local addresses. Recently, the internal network was renumbered from 192.168.0.0/24 to 10.0.0.0/24. What is the most likely cause?
⚠ Common exam trap
Cisco often tests the misconception that ping success implies full connectivity; the trap here is that ICMP can work without NAT translation if the router has a route, but TCP sessions require proper NAT entries for return traffic.
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 NAT access list still permits 192.168.0.0/24 and does not match the new 10.0.0.0/24 addresses.
The NAT access list (used with 'ip nat inside source list') still references the old 192.168.0.0/24 subnet. After renumbering to 10.0.0.0/24, the access list does not match the new inside local addresses, so PAT (overload) translation is not performed for those hosts. ICMP (ping) can still succeed if the router has a route to the internet and the packets are not translated, but HTTP sessions fail because the return traffic cannot be mapped back to the internal hosts without a NAT translation entry.
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 router's HTTP inspection rule is blocking outbound TCP port 80.
Why it's wrong here
HTTP inspection is not required for basic PAT operation; a missing inspection policy does not block HTTP translation.
- ✓
The NAT access list still permits 192.168.0.0/24 and does not match the new 10.0.0.0/24 addresses.
Why this is correct
Because the ACL that defines inside local addresses for PAT was never updated after renumbering, no dynamic translations are created for HTTP sourced from 10.0.0.0/24.
- ✗
The outside interface access list is blocking TCP packets from the new 10.0.0.0/24 subnet.
Why it's wrong here
While an outbound ACL could block HTTP while allowing ICMP, the scenario’s emphasis on the renumbering and the PAT ACL makes the NAT mismatch a more probable root cause.
- ✗
The default route has been changed to point to the wrong next-hop address, causing only HTTP packets to be dropped.
Why it's wrong here
A default route problem would affect all outbound traffic, including ICMP. Since ping succeeds, the default route is not the cause.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓The NAT access list still permits 192.168.0.0/24 and does not match the new 10.0.0.0/24 addresses.Correct answer▾
Why this is correct
Because the ACL that defines inside local addresses for PAT was never updated after renumbering, no dynamic translations are created for HTTP sourced from 10.0.0.0/24.
✗The router's HTTP inspection rule is blocking outbound TCP port 80.Wrong answer — click to see why▾
Why this is wrong here
Candidates may confuse security inspection with NAT translation, assuming that a protocol‑specific inspection is needed for HTTP.
✗The outside interface access list is blocking TCP packets from the new 10.0.0.0/24 subnet.Wrong answer — click to see why▾
Why this is wrong here
Tempting because an ACL could selectively block TCP; however, the question provides context about the renumbering, which directly points to the NAT configuration.
✗The default route has been changed to point to the wrong next-hop address, causing only HTTP packets to be dropped.Wrong answer — click to see why▾
Why this is wrong here
Candidates may assume that different protocols might take different paths, but a single default route applies uniformly to all IP traffic.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Visual reference
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Related to this question
Learn chapter
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Key term
Port Address Translation
A networking technique that maps multiple private IP addresses and their ports to a single public IP address using unique port numbers.
Key term
Ping
Ping is a network utility used to test whether a remote computer or device is reachable across an IP network and to measure the round-trip time of data packets.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 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 200-301 exam.