Do you want to check if your server is properly configured with rDNS or reverse DNS?
It’s pretty important these days to have a reverse DNS setup for your dedicated IP address in order for email to be properly delivered.
Many free email companies like GMail, Hotmail, Yahoo Mail, and others require a reverse DNS to be setup for the IP address from which the email orginiates. It would not hurt to have a SPF Record and/or a DomainKey configured as well, but that is for another post.
1) Log into your server as root or as another user.
2) Enter the following at the prompt using putty or other SSH client.
root@server [~]# dig -x 18.104.22.168 <--- replace with your IP address
The output should look like this:
;; QUESTION SECTION:
;22.214.171.124.in-addr.arpa. IN PTR
;; ANSWER SECTION:
126.96.36.199.in-addr.arpa. 1200 IN PTR w2.rc.vip.sp1.yahoo.com.
As long as there is a record in the PTR section that matches what you would like your rDNS to be such as www.server.com then your are golden.
Sometimes, you must contact your server host and have them manually enter your PTR records for you or providers will allow you to do it yourself via a control panel.