Check RDNS using NSLOOKUP command ,HOST (on linux server ) command or centralops.net.
NSLOOKUP
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1)You can check RDNS is setup or not from command prompt using nslookup command
Server which has RDNS set-
C:\>nslookup 10.11.12.13
Server: vnsc-pri.sys.gtei.net
Address: 4.2.2.1
Name: host.myhostname.com
Address: 10.11.12.13
Here if "Name" is your "hostname" then RDNS is setup for this server.
If RDNS is not setup you will see the "datacenter name " in front of "Name" as below.
C:\>nslookup 11.12.13.14
Server: vnsc-pri.sys.gtei.net
Address: 14.13.12.11
Name: bc.d3.7bae.static.theplaneet.com
Address: 11.12.13.14
Here "Name" is not your hostname, thus rdns is not set up for this server.
Using HOST command (on linux server)
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1)on server
root@shell [~]# host 10.11.12.13
output-
13.12.11.10.in-addr.arpa domain name pointer host.myhostname.com.
=> If output line is ended with hostname, then rdns is setup for this.
2)on linux server -
root@shell [~]# host 1.2.3.4
output-
4.3.2.1.in-addr.arpa domain name pointer bc.d3.7bae.static.theplanet.com.
=> output line is not ended with hostname, thus rdns is not set for this .
Use centralops.net
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browse http://centralops.net
1) open browser http://centralops.net/co/ >> Domain Dossier
put ip in it and see dns report
canonical name should be your hostname
and in dns report
13.12.11.10.in-addr.arpa IN PTR host.myhostname.com
ptr line should contain hostname.
3) open browser http://centralops.net/co/ >> Domain Dossier
put ip in it and see dns report
canonical name should be your hostname
and in dns report
"4.3.2.1.in-addr.arpa IN PTR ba.d3.7bae.static.theplanet.com"
ptr line does not contain hostname, thus no rdns set for this.
