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-   -   Reverse DNS question/problem. (http://www.linuxquestions.org/questions/linux-server-73/reverse-dns-question-problem-801748/)

kschmitt 04-13-2010 09:08 AM

Reverse DNS question/problem.
 
I'm having issues with reverse DNS, and I do have a solution, but it seems klunky, so I wanted to pass it by you folks here. Hopefully there's a more elegant way around it.

I've got a central DNS server at my main office (company.com), and another at each other facility, serving up a subdomain (plantN.company.com). The central DNS server is the master for company.com, and a slave for all of the plantN.company.com subdomains.

Forward lookups work properly against any of the DNS servers.

Against the main DNS server reverse lookups work properly for its IP ranges only.

Against the slave DNS servers, reverse lookups work properly for their own IP ranges, and ranges on the main DNS server only. (Not really a problem for me, but it may give clues...)

If I explicitly tell the main DNS server that it's a slave for a reverse zone, it works, but I need to create an entry for each triplet (ie: 172.27.24 ) in the block. There are 4 location specific DNS servers, each serving unique ranges covering 8 triplets. I know I can do it this way, but it seems, well, ugly.

The setup looks something like this:

main DNS server:
company.com (master)
plant1.company.com (slave)
...
plant4.company.com (slave)

plant1 DNS server (uses main DNS server as a forwarder):
plant1.company.com (master)
company.com (slave)

...

plant4 DNS server (uses main DNS server as a forwarder):
plant4.company.com (master)
company.com (slave)


And the relevant snippets from the main DNS servers named.conf look like this:
zone "company.com" {
type master;
file "company.com.zone";
};

zone "plant1.company.com" {
type slave;
masters { 172.27.24.100; };
};
#Which would need all this for reverse lookups to work for ONE subdomain
#works, but is ugly.
zone "24.27.172.in-addr.arpa" {
type slave;
masters { 172.27.24.100; };
};

zone "25.27.172.in-addr.arpa" {
type slave;
masters { 172.27.24.100; };
};

zone "26.27.172.in-addr.arpa" {
type slave;
masters { 172.27.24.100; };
};

zone "27.27.172.in-addr.arpa" {
type slave;
masters { 172.27.24.100; };
};

zone "28.27.172.in-addr.arpa" {
type slave;
masters { 172.27.24.100; };
};

zone "29.27.172.in-addr.arpa" {
type slave;
masters { 172.27.24.100; };
};

zone "30.27.172.in-addr.arpa" {
type slave;
masters { 172.27.24.100; };
};

zone "31.27.172.in-addr.arpa" {
type slave;
masters { 172.27.24.100; };
};

bathory 04-13-2010 03:23 PM

Hi,

A more elegant solution is the subdomain delegation for the forward zone and the
classless in-addr.arpa delegation for the reverse zone.

Regards


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