What is a DNS Lookup?
DNS (Domain Name System) is the internet's phonebook — it translates domain names into IP addresses. A DNS lookup queries these records to see how a domain is configured. For SEOs and webmasters, DNS lookups are essential for:
- Verifying domain ownership via TXT records (Google Search Console, HubSpot, etc.)
- Diagnosing email delivery issues by checking MX and SPF/DKIM/DMARC records
- Confirming CDN or hosting changes have propagated via A and CNAME records
- Checking SSL certificate restrictions via CAA records
DNS Record Types Explained
- A Record — Maps a domain to an IPv4 address. The most fundamental record — directs web traffic to your server.
- AAAA Record — Same as A but for IPv6 addresses.
- CNAME Record — Aliases one domain to another (e.g. www → example.com). Common for CDN setups.
- MX Record — Mail Exchange — directs email to the correct mail server. Lower priority number = higher preference.
- TXT Record — Text records for verification and authentication (SPF, DKIM, DMARC, domain verification tokens).
- NS Record — Name Server — identifies which servers are authoritative for the domain.
- CAA Record — Restricts which certificate authorities can issue SSL certs for the domain.
Understanding TTL and DNS Propagation
Each record has a TTL (Time to Live) value in seconds — how long resolvers cache the record. A TTL of 3600 means changes can take up to 1 hour to propagate worldwide. When making DNS changes (e.g. changing hosting), lower your TTL to 300 beforehand so changes take effect faster.