in-arpa zone for /27 subnet size

[dwalford]

Our IP provider has delegated reverse DNS for PTR to our DNS servers.

All is fine for /24 subnets but we are unable to resolve PTR requests if the IP is in a /27 subnet.

Here is what the IP provider sent to us, i used to be able to implement it in Microsoft DNS but no in Plesk 8.1

I am not able to create a zone in this format: 0.10.226.208.in-addr.arpa


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Here is some guidance on setting up reverse DNS zones for IP subnets.

Setting up classless in-addr files on your nameserver is slightly different than setting up a zone for an entire CIDR: /24 (255 IPs).

Here is an example using a hypothetical subnet, 208.226.10.0/25, or, the first 128 IPs in this CIDR: /24.

If you have 128 IP addresses in a particular block we would make the following entries into the CIDR: /24 zonefile on 'Verizon' servers:

10.226.208.in-addr.arpa

0 IN NS dns1.yourdomain.com.
0 IN NS dns2.yourdomain.com.
1 IN CNAME 1.0.10.226.208.in-addr.arpa.
2 IN CNAME 2.0.10.226.208.in-addr.arpa.
3 IN CNAME 3.0.10.226.208.in-addr.arpa.

This points all queries for the first 128 IP addresses to a zone on your nameserver called 0.10.226.208.in-addr.arpa.

The zonefile you create will look just like a normal zonefile (with PTR records etc.), only the zone file name will have a 4th octet noting the net address, or first IP in your subnet ......
(i.e. 0.10.226.208.in-addr.arpa).

Here is a sample of what your zonefile should look like:
[0.10.226.208.in-addr.arpa]

1 IN PTR name.yourdomain.com.
2 IN PTR host.yourdomain.com.
3 IN PTR user.yourdomain.com.

OR

1.0.10.226.208.in-addr.arpa. IN PTR name.yourdomain.com.
2.0.10.226.208.in-addr.arpa. IN PTR host.yourdomain.com.
3.0.10.226.208.in-addr.arpa. IN PTR user.yourdomain.com.

For more info on subnetted in-addr on an NT machine you can also see the Microsoft website's white paper:
http://support.microsoft.com/support/kb/articles/q174/4/19.asp

Windows GUI may not let you edit the named.boot file manually, so this might not apply to you. If you are using BIND or a similar platform you should put the following directive into your named.boot file:

primary 0.10.226.208.in-addr.arpa db.reversefilename

BIND named.conf would look similar to:

zone "0.10.226.208.in-addr.arpa" {
type master;
file "0.10.226.208";
};

For more information about Classless IN-ADDR.ARPA Delegation, please see RFC2317. http://www.faqs.org/rfcs/rfc2317.html

 

[sergius]

Hello dwalford,

Thank you for the report.
Unfortunately you are right. Plesk does not allow manage reverse zone properly. However we are going to fix it in future versions.
Now I only can suggest you to create it manually. Plesk will not touch it.