What does "PTR record" mean?

Hey guys,
What does "PTR record" mean? Does it have any relations to rDNS?
Please explain me, your opinion would be appreciated!

Gmeister4 said:

Hey guys,
What does "PTR record" mean? Does it have any relations to rDNS?
Please explain me, your opinion would be appreciated!

Click to expand...

Yes / correct PTR / rDNS or reverse dns which points an IP to the host name - needed for if you intend to run mail on that dedicated IP as some MTA's may reject mail if coming from a IP with no PTR Record see here:

Pointer records are used to map a network interface (IP) to a host name. These are primarily used for reverse DNS.

Name: This usually represents the last octet of the IP address.
System (PTR to): This will be the value (the reverse DNS) for your host / computer within your domain.
TTL: The TTL (Time to Live) is the amount of time your record will stay in cache on systems requesting your record (resolving nameservers, browsers, etc.). The TTL is set in seconds, so 60 is one minute, 1800 is 30 minutes, etc.
Best Practice Tip
If you plan on changing your reverse DNS TTL to a low value a few hours before you make the change (especially for mail servers). This way you won't have any downtime during the change. Once your reverse DNS changes you can always raise your TTL to a higher value again.

More info here:

http://help.dnsmadeeasy.com/managed-dns/dns-record-types/ptr-record/

Dave

I assume. You may have come here cause you've been told that you need a PTR / Reverse DNS record to avoid rejections from sites like AOL and others. A PTR record (also called a "host PTR record") is what lets someone do a "reverse" DNS lookup - that is, they have your IP address and want to know what your host is.

It is important cause it convenience, because of the abuse of the internet by spammers, certain emails has grown up. For example, you may not be able to send email to some of the sites if you don't have a valid PTR record.

Simply put A PTR record is the same as an A record that works in reverse so IP's can be resolved into host names.

HostPace said:

I assume. You may have come here cause you've been told that you need a PTR / Reverse DNS record to avoid rejections from sites like AOL and others. A PTR record (also called a "host PTR record") is what lets someone do a "reverse" DNS lookup - that is, they have your IP address and want to know what your host is.

It is important cause it convenience, because of the abuse of the internet by spammers, certain emails has grown up. For example, you may not be able to send email to some of the sites if you don't have a valid PTR record.

Click to expand...

LJSHost said:

Simply put A PTR record is the same as an A record that works in reverse so IP's can be resolved into host names.

Click to expand...

Can you please tell me where to set PTR record and where to set reverse DNS?

Reverse DNS will be set at my hosting control panel and PTR record will be set at my domain control panel?

You need to find out the name servers for your domain e.g ns1.yourdoamin.com ns2.yourdomain.com
This information can be found by doing a whois on your domain name.

The PTR record is added in the dns zone for your domain on those servers. This can be done via cPanel/Control panel (if your domain is with your hosting provider) if your domain dns is hosted elsewhere you will need to make the change with whom ever has control over your dns.

Sorry can't be more helpful without knowing all the details, domain name etc.

This is a real example of the PTR record

100.0.168.192.in-addr.arpa. IN PTR mailserver.example.com

The 100.0.168.192 part is the ip written in reverse.
The mailserver.example.com is the name of the mail server.

As stated in my previous post this record needs to be added to the domains DNS zone on the name server that is serving your domains DNS. Explaining exactly how this is done varies with different hosting platforms and DNS management interfaces provided by hosting firms.

If you don't feel comfortable enough with how DNS works to make these changes yourself, speak to your hosting provider or domain provider (if your DNS is with them) as they will make the changes for you. Hope this helps.

To put it simply A PTR record is equivalent to a b record that actually works backwards so IP's could be resolved into host names.

PTR record can be considered as opposite for A record. PTR record resolves IP address to the domain name and A record resolved domain to IP address. An A record should exist for all PTR records. By using the below command you can check whether PTR record is set for an IP or not.

dig -x IP
host IP

So PTR are used for reverse Domain Name System lookup

Its simple, the idea of DNS is take an Domain and translate it to an IP.
The simple records like: A, AAA etc..
lets take the domain: google.com, the DNS translate google.com to 82.102.187.110 ( in my country )

Now the reverse dns takes the IP and translate it to a domain.

If a A record translates:
xxx.com -> x.x.x.x
so the PTR translate:
x.x.x.x to xxx.com

simple and easy

Most of the datacenters have the PTR translate to the ISP you are using.
like;
a.b.c.d -> a.b.c.d.isp-network-name.net