nslookup
nslookup is a command-line network administration tool used for querying the Domain Name System (DNS) to obtain domain name or IP address mappings, or other DNS records. It is commonly available on Unix-like systems, Windows, and macOS, and is used for troubleshooting DNS issues, verifying DNS configurations, and performing DNS lookups interactively or non-interactively.
Developers should learn nslookup for debugging network connectivity problems, verifying DNS propagation after changes, and testing DNS server responses during application development or system administration. It is particularly useful in scenarios like diagnosing website accessibility issues, checking mail server records (MX), or ensuring proper domain resolution in distributed systems.