I've added a DNS record but it doesn't work

The most common mistake is forgetting the period at the end of CNAME or MX records. Make sure that the value of your CNAME or MX record ends with a period, for example:

     www IN 10800 CNAME web.example.com. (notice the period in "web.example.com.")
     @ IN 10800 MX 10 mail.example.com. (notice the period in "mail.example.com.")

Keep in mind that any changes to your DNS records may take a few hours to be reflected (sometimes referred to as "propagated")

Managing DNS records