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in-arpa zone for /27 subnet size

D

dwalford

Guest
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
 
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.
 
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