What is a DNS lookup?
DNS is the internet's address book: it translates a human-friendly domain into the machine addresses and routing that make the web and email work. A DNS lookup asks the name servers for a domain what records they currently publish — so you can confirm where a site points, how its mail is routed, and whether anything has changed unexpectedly.
The record types, explained
- A — maps the domain to an IPv4 address (where the website lives).
- AAAA — the same idea for IPv6 addresses.
- MX — the mail servers that accept email for the domain, in priority order.
- NS — the authoritative name servers that hold the domain's DNS.
- TXT — free-form records used for verification and email policy (SPF, DKIM, domain ownership checks).
Reading TTL and propagation
Every record carries a TTL — the number of seconds resolvers may cache it. When you change a record, the old value can linger anywhere it's cached until that TTL expires, which is why a change seems to "take a while to go live". Lowering TTL ahead of a planned change makes it propagate faster.
Common DNS problems to look for
A missing or wrong A record sends visitors nowhere or to the wrong server. Missing MX records — or a broken SPF in TXT — quietly break email deliverability. Unexpected name-server changes can indicate a hijack or an account compromise. Because DNS changes take effect silently, the damage is often done before anyone notices; seeing the records is how you catch it.
From a lookup to change alerts
A lookup shows today's records. What you really want to know is when they change — especially if you didn't make the change. DNS monitoring in Domain Monitor Hub watches your A, AAAA, MX, NS and TXT records and alerts you the instant any of them move, so an accidental edit or a hijack never goes unnoticed. Look a domain up here; let the app keep watch.