When an organization moves its DNS servers to new IP addresses, the NS (Name Server) records must be updated. The NS record defines which DNS servers are authoritative for a domain. Ifthese records still point to the old IP addresses, clients will continue to query the outdated servers, leading to connectivity issues.

Breakdown of Options:

A. AAAA – This record maps a domain name to an IPv6 address. Since the issue is with DNS resolution, not IP versioning, this is incorrect.

B. CNAME – A CNAME (Canonical Name) record is used for domain aliasing, not for defining authoritative name servers.

C. MX – Mail Exchange (MX) records direct email traffic to the correct mail server, which does not impact general website accessibility.

D. NS – Correct answer. NS records must be updated to reflect the new authoritative DNS servers.