Addresses back to names.
WHAT IT IS
A record mapping an address back to a hostname.
WHERE IT IS CONTROLLED
By whoever controls the address, not by you.
For hosting, that is the provider.
WHY IT MATTERS
Receiving mail servers check it.
A mismatch or absence affects mail delivery.
WHAT IT SHOULD BE
A name that matches forward to the same address.
WHO SETS IT
On shared hosting, the provider.
On your own server, you request it from whoever provides the address.
WHEN TO CHECK IT
When mail delivery is poor and authentication appears correct.
WHAT IT DOES NOT AFFECT
Web traffic, in practice.
WHAT ELSE USES IT
Some logging and diagnostic tools display names rather than addresses.
WHAT TO DO IF IT IS WRONG
Ask the provider of the address.
You cannot set it in your own DNS.
WHAT TO VERIFY
That forward and reverse agree.
