Domain Name Servers (DNS) map from domain name to the IP address of the server hosting the website / email.
Basic site example.com (hosted at IP 192.0.2.1) and www.example.com:
| Entry | Type | TTL | Target |
|---|---|---|---|
| @ | A | 192.0.2.1 | |
| www | CNAME | example.com |
The @ entry refers to your origin, which in this case is example.com.
www is configuring the subdomain www.example.com, by pointing it to example.com.
In this example the TTL will have defaulted.
Default TTL
Time To Live (TTL) is the amount of time, in seconds, that a slave DNS server will cache the DNS entry. A common default is 86400 seconds == 24 hours.
Avoid wildcards
Do not use a wildcard entry (the asterisk *) to catch all subdomains, because…
- People can put any old crap at the front of your domain name and it will still work e.g. do.not.trust.mindspill.net.
- Domain searches could resolve to your domain e.g. www.google.com.mindspill.net, which can happen automatically via your DNS resolver or third party services e.g. search engines.
