DNSLookups

DNS lookups refer to the process of resolving a domain name into an IP address or other DNS records by querying the Domain Name System. They are a core part of Internet name resolution, performed by client software, recursive resolvers, and authoritative name servers.

In a typical lookup, a client asks a resolver. The resolver may perform the recursion itself or delegate. If recursive, the resolver starts at root servers, then top-level domain servers, then authoritative servers for the domain. The process may end with a definitive answer or a referral to another server. Iterative queries return referrals.

The DNS stores records such as A (IPv4 address), AAAA (IPv6 address), CNAME aliases, MX mail servers, NS delegation, TXT, and PTR for reverse lookups. DNS lookups may target different record types depending on the need.

Responses are cached at multiple levels to reduce latency. Time-to-live values control how long records are kept. Caching improves performance but can cause stale results if records change.

Security features include DNSSEC to verify integrity, while privacy-oriented options like DNS over TLS and DNS over HTTPS encrypt queries between client and resolver.

Practical aspects include the use of common command-line tools such as dig, nslookup, and host. Dozens of public resolvers exist; misconfigurations or DNS poisoning can cause outages or misdirected traffic.