DNS Record
Definition
Records are the contents of a zone — the list your nameservers answer from. Every record has the same four parts however the editing form is laid out: the host it applies to, a type, the value, and a time to live in seconds. The type carries all the meaning. An A record's value is an IPv4 address, a CNAME record's value is another hostname, a TXT record's value is free text, an MX record's value is a mail server with a priority number. One host can hold several records of the same type and several types at once, with a single exception: a name holding a CNAME may hold nothing else beside it.
Why It Matters
Almost every case of "I pointed my domain and nothing happened" ends at a record — the wrong type, the wrong host field, or an old one still sitting beside the new one. Resolvers have no opinion about what you meant; they return what is in the zone. Two A records for two different hosts is not an error, it is a load-balancing instruction, and visitors will be split between a working site and a dead one at random. Records are also the only part of the setup a host cannot fix for you, because they live at your provider and are edited with your credentials.
How It Works
You edit records wherever the authoritative nameservers for the domain are run — that may be the registrar, a dedicated DNS provider, or the host itself. A save publishes to the zone almost immediately, and from that moment every fresh query gets the new value. Queries that were answered before your edit keep the old value until the TTL on the previous record runs out, which is the entire reason a change can seem not to take. A checking tool that queries the nameservers directly shows you the truth straight away; a browser shows you a cache.
Real-World Example
To serve a 40 MB press kit from files.hart.co.uk on 99helpers, you add exactly one record: host 'files', type CNAME, value the target hostname the dashboard gives you, TTL 300. Nothing else in the zone is touched, so the website at the apex and the mail records carry on as before. If the press kit later moves, the same single record is edited and every link in circulation follows it.
Common Mistakes
- ✕Leaving a stale A record next to a new CNAME — the zone is invalid and answers become a coin toss
- ✕Ignoring the host field convention — some forms want the bare label, some want the full name, and the wrong guess creates files.acme.com.acme.com
- ✕Editing at the registrar when a third-party provider is delegated — the records are real, saved and completely unread
Related Terms
A Record
An A record maps a name straight to an IPv4 address. It is the simplest record there is, and the only standard way to put a destination at the bare version of a domain.
CNAME Record
A CNAME record points one name at another name rather than at an address. Hosts ask for them because the addresses behind their target hostname can then change without you touching your zone.
TXT Record
A TXT record holds plain text at a DNS name. For anyone hosting files or a site, the reason you meet one is domain verification — proving to a provider that the name really is yours.
DNS TTL
TTL is the number of seconds a DNS answer may be cached before it has to be fetched again. It is set per record, and it decides how long a mistake lasts.
Public URL
An address that serves its content to anyone who requests it, with no sign-in, token or password. Having the address is the only requirement.
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