What are PTR (Pointer) Records?
Pointer records are used to map a network interface (IP) to a hostname for a reverse DNS configuration. PTR records are configured within reverse DNS domains (in-addr.arpa) domains.
PTR Record Fields
|Name||The last octet of the IP address you are configuring reverse DNS for.|
|TTL||The TTL (Time to Live) in seconds is the amount of time the record will cache resolving name servers and in web browsers. The longer the TTL the less frequent remote systems will lookup the DNS record and the less query traffic the domain receives. The shorter the TTL the faster DNS changes propagate in servers that have cached data, however the higher the volume of query traffic the domain receives.
Records configured with Failover or that change often should have TTL’s set anywhere from 180 to 600 (3 to 10 minutes cache).
Records that are static and don’t change often should have TTL’s set between 1800 (being on the low end) to 86400 seconds (30 minutes to 1 day cache).
If a change is needed for a record with a high TTL, the TTL can be lowered prior to making the change and then raised back up again after.
|System||This will be the host name of the computer or server the IP resolves to, for example mail.example.com. It is important to note, the domain name is automatically appended to the end of this field unless it ends with a dot (.).|
Reverse DNS Overview
Before you set up your PTR records, you should first go through the Reverse DNS tutorial and set up Reverse DNS domains on Constellix name servers.
4. In this screen, you will add the record information. Follow the steps below:
A) Name: This will be the hostname for your record. It is important to note, the domain name is automatically appended to the “Name” field of the record.
B) TTL: Edit the TTL. Time to Live is measured in seconds and is the amount of time the record will cache in resolving name servers and web browsers.
C) System: This will be the host name of the computer or server the IP resolves to.
D) Notes: Add a helpful note with keywords so you can search for your records later.
E) Save and Close: Save your changes. Don’t forget to commit your changes.