A, MX, TXT, NS: What All Your DNS Records Actually Do
A domain name is really just a set of DNS records pointing to different things - a website, a mail server, a verification token for some third-party service. Most people only ever think about DNS when something’s broken, which is exactly when the different record types start to matter.
The record types you’ll actually run into
- A - maps a domain to an IPv4 address. This is the one most people think of as “DNS.”
- AAAA - the same thing, but for IPv6 addresses.
- CNAME - points a domain to another domain name instead of an IP directly. Common for subdomains handled by a third-party service (a CDN, a hosting platform).
- MX - specifies which mail servers handle email for the domain, in priority order. If your MX records are wrong, incoming mail bounces or vanishes - independently of whether your website works fine.
- TXT - arbitrary text attached to a domain, used for two very different things in practice: proving domain ownership to services like Google Search Console, and email authentication (SPF and DMARC records are both just TXT records with a specific format). Our SPF, DKIM & DMARC Checker breaks down that side of TXT records specifically.
- NS - lists the authoritative nameservers for the domain - the servers that actually answer for every other record type above. If these are wrong, nothing else matters; queries won’t even reach the right place.
Why a domain can “work” for one thing and not another
Because these are independent record types, a domain can have a perfectly working website (correct A record) while its email is completely broken (missing or wrong MX record), or vice versa. This trips people up constantly when migrating hosting or email providers - updating one without the other leaves half the domain functional.
Checking any domain’s records
Our DNS Lookup Tool queries A, AAAA, MX, TXT, NS, and CNAME records for any domain, plus a reachability comparison: a global DNS lookup against a live connection attempt from your own browser on your current network. A mismatch there can point to DNS-level blocking or filtering - something we’ve written about specifically in the context of why some sites don’t load on Jio or Airtel.
When DNS looks fine but the site still doesn’t load
Correct DNS records only get you as far as “the server should be reachable.” If DNS resolves correctly but the site still won’t load, that’s a different class of problem - our post on telling a genuine outage apart from a network-specific block walks through how to narrow that down.