300-445 Question 125
Select 3Your organization has implemented an enterprise-grade network monitoring solution to ensure DNS availability and performance. Recently, users have reported intermittent DNS resolution failures. Upon investigation, you find that the DNS server is reachable, but the failures persist. Which of the following actions should you take to diagnose and resolve the issue?
- A
Check for high response times or timeouts in the DNS query logs.
- B
Verify if the DNS server has exceeded its query rate limits.
- C
Inspect the firewall rules to ensure DNS traffic is not being blocked.
- D
Perform a reverse DNS lookup on the affected domain names and compare the results.
- E
Ensure DNSSEC is properly configured and not causing validation issues.
Show answer and explanation
Correct answers: A, B, E
Explanation
In this scenario, the DNS server is reachable, so the focus should be on identifying issues with its performance, rate limits, or DNSSEC configuration. High response times or query drop rates could indicate server-side problems, while DNSSEC misconfiguration can cause validation errors, leading to intermittent resolution failures. Checking the firewall or performing reverse lookups is not directly relevant to the symptoms described.
- A. Correct.
High response times or timeouts in query logs can indicate performance issues with the DNS server, such as resource constraints or load-related problems.
- B. Correct.
If the DNS server has exceeded its query rate limits, it may start dropping requests, leading to intermittent failures.
- C. Incorrect.
While inspecting firewall rules is a valid troubleshooting step, the DNS server is already reachable, so this is unlikely to be the root cause.
- D. Incorrect.
Reverse DNS lookups are typically not required for standard DNS resolution issues and are unrelated to the problem described in the scenario.
- E. Correct.
Improperly configured DNSSEC can lead to validation failures, causing intermittent issues in DNS resolution.