Reverse DNS Lookup Online
What is PTR record in DNS?
PTR (from "PoinTeR") - is a reverse DNS record (rDNS), which associate an IP address with domain name. "Reverse" to DNS A record, which associate domain name with IP address.
What is PTR record used for, any examples?
PTR record often used by receiving mail servers as an important part of anti-spam filtration. If you are sending an emails from your own server / domain name and want they will come to "Inbox" folder, not "Spam" / "Junk", you need to have a correct PTR record on your sending IP address - value of PTR must match name of your mail server (which specified in HELO / EHLO).
E.g. you send an emails with "from" address firstname.lastname@example.org from ip address 126.96.36.199, your mail server is mail.yourdomain.com - in this case the PTR record for ip 188.8.131.52 must be exactly mail.yourdomain.com, not a just domain name yourdomain.com how often people think wrongly.
How to make a PTR record?
PTR records can edit only the IP addresses owners, so you just need to contact your server / hosting support and ask them to make a PTR records you need.
Is it possible to make a few PTR records for 1 ip address?
No, it's impossible, there is a strict DNS rule - one ip address can have only one PTR record.