300-445 Question 122
Select 3An enterprise network administrator has implemented a DNS-based load balancing solution to improve application availability. However, users report intermittent failures when trying to access the application. Upon investigation, it is found that some DNS responses are not being cached by client devices as expected. Which of the following actions should the administrator take to resolve the issue?
- A
Increase the Time-To-Live (TTL) value in the DNS configuration.
- B
Verify that all DNS records for the load balancer are configured with the same priority.
- C
Implement DNS Response Rate Limiting (RRL) on the DNS server to reduce the number of queries.
- D
Ensure the DNS server is returning valid A or AAAA records for all requested domains.
- E
Check for misconfigurations in the DNS resolver settings on the client devices.
Show answer and explanation
Correct answers: A, D, E
Explanation
The issue stems from DNS caching and resolution. Increasing the TTL value (Option 1) helps ensure responses are cached for longer, reducing the frequency of resolution failures. Verifying the DNS server's response integrity (Option 4) ensures clients receive valid records, and checking client resolver settings (Option 5) addresses any misconfigurations preventing caching. These combined actions improve DNS reliability and resolve the intermittent failures.
- A. Correct.
Increasing the TTL value ensures that DNS responses are cached for a longer period, reducing the frequency of queries and improving reliability.
- B. Incorrect.
Configuring the same priority for DNS records is unrelated to caching issues. It affects load balancing behavior but not caching.
- C. Incorrect.
DNS Response Rate Limiting (RRL) is used to prevent denial-of-service attacks and does not address caching problems.
- D. Correct.
Valid A or AAAA records are necessary for proper DNS resolution. Invalid records can result in failures when clients attempt to cache or connect.
- E. Correct.
Misconfigurations in DNS resolver settings on clients can prevent proper caching or resolution, leading to intermittent failures.