The correct answer is to configure R1 to use a different DNS server, such as 198.51.100.10, that holds the valid A record for server.example.com. This is necessary because the original DNS server at 203.0.113.10 is returning an NXDOMAIN response, meaning it lacks the correct mapping for that hostname; since the ping to the IP address succeeds, the issue is purely with the DNS resolution data, not with routing or connectivity. On the CCNA 200-301 v2 exam, this scenario tests your ability to distinguish between network reachability and DNS server reliability—a common trap is to waste time clearing the DNS cache or enabling ip domain-lookup, when the real fix is pointing to a properly configured DNS server. Remember that a successful ping to an IP proves Layer 3 works, so focus on the DNS server’s record quality, not the router’s lookup settings. Memory tip: “If the IP pings but the name stings, the DNS server’s the thing.”
CCNA Network Services and Security Practice Question
This 200-301 practice question tests your understanding of network services and security. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Network Topology
You are connected to R1, a Cisco IOS-XE router. The network uses a DNS server at 203.0.113.10 for name resolution. Users report that 'ping server.example.com' fails, but 'ping 203.0.113.50' succeeds. Assume proper routing is configured between R1 and the DNS server. Diagnose and resolve the DNS resolution issue so that the hostname resolves correctly, and verify the fix using appropriate Cisco IOS commands (e.g., ping, show hosts, debug domain).
R1# show running-config | section ip domain
ip domain lookup
ip name-server 203.0.113.10
ip domain timeout 1
!
R1# show ip dns
DNS lookup is enabled
DNS server 203.0.113.10
DNS timeout 1 seconds
Default domain name: example.com
!
R1# nslookup server.example.com
Server: 203.0.113.10
Address 1: 203.0.113.10
Name: server.example.com
Address 1: 203.0.113.50
!
R1# dig server.example.com
; <<>> DiG 9.8.3 <<>> server.example.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 12345
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;server.example.com. IN A
;; ANSWER SECTION:
(empty)
;; AUTHORITY SECTION:
(empty)
;; ADDITIONAL SECTION:
(empty)
;; Query time: 1 msec
;; SERVER: 203.0.113.10#53(203.0.113.10)
;; WHEN: Thu Jan 11 12:34:56 2024
;; MSG SIZE rcvd: 34
A
Configure R1 to use a different DNS server, such as 198.51.100.10, that has the correct A record for server.example.com.
This is correct because the current DNS server (203.0.113.10) returns NXDOMAIN for server.example.com, as confirmed by dig. Changing to a DNS server that has the proper A record resolves the issue. After configuration, nslookup and dig will return the correct IP address.
B
Add the command 'ip domain lookup' under global configuration to enable DNS resolution on R1.
Why wrong: This is incorrect because 'ip domain lookup' is enabled by default on Cisco IOS-XE routers. Since ping to the IP address works, DNS resolution is already enabled; the issue is with the DNS server's response.
C
Clear the DNS cache on R1 using 'clear ip dns cache' to remove any stale entries.
Why wrong: This is incorrect because the dig command shows the authoritative response from the DNS server is NXDOMAIN, not a cached result. Clearing the cache would not fix the missing A record on the DNS server.
D
Configure the router to use the IP address 203.0.113.50 as the DNS server instead of 203.0.113.10.
Why wrong: This is incorrect because 203.0.113.50 is the IP address of server.example.com, not a DNS server. Configuring it as a name-server would cause DNS queries to fail entirely.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Configure R1 to use a different DNS server, such as 198.51.100.10, that has the correct A record for server.example.com.
The issue is that the DNS server at 203.0.113.10 does not have a valid A record for server.example.com, returning NXDOMAIN. Since ping to the IP address works, connectivity is fine. To resolve, configure R1 to use a different DNS server (e.g., 198.51.100.10) that has the correct A record. After configuration, verify with 'show hosts' to see the resolved hostname entry and 'ping server.example.com' to confirm successful resolution. The options involving DNS cache clearing or enabling domain lookup are irrelevant because the problem lies with the DNS server itself, not with caching or disabled DNS lookup.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Configure R1 to use a different DNS server, such as 198.51.100.10, that has the correct A record for server.example.com.
Why this is correct
This is correct because the current DNS server (203.0.113.10) returns NXDOMAIN for server.example.com, as confirmed by dig. Changing to a DNS server that has the proper A record resolves the issue. After configuration, nslookup and dig will return the correct IP address.
Related concept
Read the scenario before looking for a memorised answer.
✗
Add the command 'ip domain lookup' under global configuration to enable DNS resolution on R1.
Why it's wrong here
This is incorrect because 'ip domain lookup' is enabled by default on Cisco IOS-XE routers. Since ping to the IP address works, DNS resolution is already enabled; the issue is with the DNS server's response.
✗
Clear the DNS cache on R1 using 'clear ip dns cache' to remove any stale entries.
Why it's wrong here
This is incorrect because the dig command shows the authoritative response from the DNS server is NXDOMAIN, not a cached result. Clearing the cache would not fix the missing A record on the DNS server.
✗
Configure the router to use the IP address 203.0.113.50 as the DNS server instead of 203.0.113.10.
Why it's wrong here
This is incorrect because 203.0.113.50 is the IP address of server.example.com, not a DNS server. Configuring it as a name-server would cause DNS queries to fail entirely.
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.
✓Configure R1 to use a different DNS server, such as 198.51.100.10, that has the correct A record for server.example.com.Correct answer▾
Why this is correct
This is correct because the current DNS server (203.0.113.10) returns NXDOMAIN for server.example.com, as confirmed by dig. Changing to a DNS server that has the proper A record resolves the issue. After configuration, nslookup and dig will return the correct IP address.
✗Add the command 'ip domain lookup' under global configuration to enable DNS resolution on R1.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that 'ip domain lookup' is not the cause of the problem; it is already enabled by default.
Why candidates choose this
Candidates might think that DNS resolution is disabled because the hostname fails to resolve, but the command is on by default and not the root cause.
✗Clear the DNS cache on R1 using 'clear ip dns cache' to remove any stale entries.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the problem is not a cached negative response; the DNS server itself lacks the record.
Why candidates choose this
Candidates often confuse caching issues with authoritative DNS misconfigurations. Since nslookup might show a different result due to caching, they may think clearing the cache helps.
✗Configure the router to use the IP address 203.0.113.50 as the DNS server instead of 203.0.113.10.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that 203.0.113.50 is a host address, not a DNS server address.
Why candidates choose this
Candidates might see that ping to 203.0.113.50 succeeds and mistakenly think it can serve as a DNS server, confusing the target host with a name server.
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?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Trap categories for this question
Command / output trap
This is incorrect because the dig command shows the authoritative response from the DNS server is NXDOMAIN, not a cached result. Clearing the cache would not fix the missing A record on the DNS server.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 200-301 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
Identify which 200-301 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Network Services and Security — This question tests Network Services and Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Configure R1 to use a different DNS server, such as 198.51.100.10, that has the correct A record for server.example.com. — The issue is that the DNS server at 203.0.113.10 does not have a valid A record for server.example.com, returning NXDOMAIN. Since ping to the IP address works, connectivity is fine. To resolve, configure R1 to use a different DNS server (e.g., 198.51.100.10) that has the correct A record. After configuration, verify with 'show hosts' to see the resolved hostname entry and 'ping server.example.com' to confirm successful resolution. The options involving DNS cache clearing or enabling domain lookup are irrelevant because the problem lies with the DNS server itself, not with caching or disabled DNS lookup.
What should I do if I get this 200-301 question wrong?
Identify which 200-301 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. You are connected to R1, a Cisco IOS-XE router that serves as the DNS resolver for the local network. The router can reach the DNS server at 198.51.100.53, but internal hosts cannot resolve the hostname 'fileserver.courseiva.com' (expected IP 203.0.113.10). Which configuration will resolve the issue?
hard
✓ A.Add a static host entry: ip host fileserver.courseiva.com 203.0.113.10
B.Change the DNS server to 203.0.113.53 using the command 'ip name-server 203.0.113.53'
C.Add a static route to 198.51.100.53 via the next-hop interface
D.Configure the router to use the DNS server at 8.8.8.8 using 'ip name-server 8.8.8.8'
Why A: The DNS server is reachable but does not have an A record for fileserver.courseiva.com, so NXDOMAIN is returned. The router can resolve the name locally by adding a static host entry with `ip host`. This bypasses the external DNS and directly maps the hostname to the correct IP. Changing the DNS server to another unknown IP does not guarantee resolution, and static routes or external public DNS are irrelevant for this internal name.
Last reviewed: Jun 6, 2026
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