What is the main function of the nslookup command?

• A. To ping a host
• B. To trace a route to a host
• C. To perform whois on a domain
• D. To query DNS records for a domain

Answer: (D)

nslookup is a utility used to query DNS records for a domain. It asks DNS servers to reveal information about a domain, such as its IPv4 address (A records), IPv6 address (AAAA records), mail servers (MX records), authoritative name servers (NS records), or other text data (TXT records). This helps you verify what a DNS server is returning for a domain and diagnose resolution issues, misconfigurations, or propagation delays. You can specify the type of record you want and even target a specific DNS server to query.

The other options serve different purposes: ping checks reachability using ICMP, traceroute maps the network path to a host, and whois retrieves registration information about a domain. The essential role of nslookup is directly querying DNS records for a domain.