DNS translates human-readable domain names into the information computers actually need — IP addresses, mail server destinations, ownership verification tokens, and more. A domain doesn't have just one DNS record; it has several different types, each answering a different question. Knowing what each one does makes DNS lookups a lot less mysterious.
The record types you'll actually run into
- A — maps a domain to an IPv4 address. This is the most common record and the one that determines “where does this domain's website live.”
- AAAA — the same idea as an A record, but for IPv6 addresses.
- MX — mail exchange records. They tell the internet which mail server(s) handle email for a domain, and in what priority order. This is the record that's wrong most often when “email just isn't arriving” — this is what people usually mean by “MX tools.”
- TXT — free-form text records used for all kinds of verification and policy: domain ownership proof, SPF (which servers are allowed to send mail for this domain), DKIM keys, and various third-party service verification codes.
- CNAME — an alias that points one hostname to another hostname, rather than directly to an IP. Common for subdomains pointing at a hosting provider or CDN.
- NS — name server records, declaring which DNS servers are authoritative for a domain, i.e. which servers actually hold the real answers.
Forward lookup vs. reverse lookup
A forward lookup is the everyday case: you have a domain name and want its records (an A record's IP, an MX record's mail server, and so on). A reverse lookup runs the other direction — given an IP address, it finds the hostname (PTR record) associated with it. Reverse lookups are especially useful for checking mail server reputation — most receiving mail servers treat a missing or mismatched reverse DNS entry as a strong spam signal, and some reject outright — and for identifying what a given IP address actually is.
Why MX records deserve special attention
Unlike an A record, a broken MX record often fails silently — there's no error page, nothing visibly “down.” Mail simply stops arriving, or gets rejected by the sending server with a bounce the recipient never sees. A quick MX lookup after any domain or hosting change is one of the cheapest ways to catch a mail outage before it becomes “why didn't you respond to my email from three days ago.”
Why TXT records matter more than they look
TXT records look like clutter — a pile of odd strings — but they quietly control real things: whether a mail server is allowed to send on a domain's behalf (SPF), whether outgoing mail is cryptographically signed (DKIM), and domain ownership verification for services like Google Workspace, Microsoft 365, or CDN providers. Deleting a TXT record you don't recognize during cleanup is a common, avoidable way to break email deliverability or lose a service integration.
A neutral resolver matters
DNS results can differ depending on which resolver answers — your ISP's resolver might have cached an old record, while a neutral public resolver returns the current one. Looking records up from a server-side, neutral resolver avoids that ambiguity and shows you what the wider internet is actually seeing, rather than whatever happens to be cached on your own machine.
If different resolvers seem to disagree with each other after a recent change, that's exactly what a DNS propagation checker is built to show you.
Run a lookup yourself with the DNS lookup tool — query all record types at once, or drill into just MX, TXT, or any other single type.