Multiple DNS Forwards

[Dave Walsh]

Below is the content of my original question and the answer (from the BIND
archives). Your solution worked great. However, our partner company has now
expanded or decentralized and they also have more than just partner.com
names to resolve. They now have hal.us.partnerco.com. I tried putting in
another entry in my named.conf, but it doesn't seem to resolve hosts in
hal.us.partnerco.com, but partner.com does still work.

Any ideas?

TIA

Dave



EXAMPLE: named.conf

=====================

options {

directory "/var/named";

forwarders { 227.252.18.10; };

forward only;

query-source address * port 53;

};

zone "0.0.127.IN-ADDR.ARPA" in {

type master;

file "db.127.0.0";

notify no;

};

zone "mycompany.ca" in {

type master;

file "db.mycompany";

};

** NOTE: I CAN RESOLVE HOSTS IN PARTNER.COM

zone "partner.com" {

type forward;

forward only;

forwarders { 158.138.120.22; }

}

** NOTE: I CAN'T RESOLVE HOSTS IN HAL.US.PARTNERCO.COM

zone "hal.us.partnerco.com" {

type forward;

forward only;

forwarders { 158.138.120.22; }

}

zone "57.168.192.IN-ADDR.ARPA" in {

type master;

file "db.192.168.57";

};

zone "0.1.10.IN-ADDR.ARPA" in {

type master;

file "db.10.1.0";

};

zone "0.30.10.IN-ADDR.ARPA" in {

type master;

file "db.10.30.0";

};



zone "148.208.198.IN-ADDR.ARPA" in {

type master;

file "db.198.208.1481";

};

// zone "." in {

// type hint;

// file "db.cache";

// };

END NAMED.CONF





ORIGINAL CORRESPONDENCE

There is really no such thing as "conditional" forwarding in BIND 8. There

is, however, "selective" forwarding. The difference is more than semantic:

selective forwarding works *unconditionally*, i.e. has no relation to

events or state, but is specified on a zone-by-zone basis, i.e. all queries

in a specific zone X should be forwarded to a specific set of servers Y, Z,

etc.. In your case, you'd set up a zone of type "forward" for your business

partner's domain, let's call it "partner.com". And also in the zone

definition you'd specify "forward only" and a "forwarders" clause

containing the addresses of the partner's nameservers. So it would look

something like:

zone "partner.com" {

type forward;

forward only;

forwarders { x.x.x.x; y.y.y.y; };

}

In your situation, selective forwarding would probably be better than

conditional forwarding anyway, which would waste time and resources sending

queries to the wrong places.

A couple of other alternatives to consider, depending on your performance

characteristics and/or requirements, or redundancy requirements, would

include stub or slave zones.



- Kevin

Dave_Walsh wrote:

> We are a satellite organization of our parent organization. At present,

>

> all of our Win95 PCs point to my local DNS server with a forward

> statement

> to our parent organization's DNS server for name resolution. In other

> words, anything not resolved locally, will be forwarded to our corporate

>

> head office (where our Internet access is also). We've recently

> acquired a

> project with a business partner that requires only our location to have

> access to the partner's DNS server so I can resolve names in their name

> space.

>

> What's the best approach to accomodate all my needs? I must be able to

> resolve local IP names, corporate names in the corporate WAN, Internet

> names (via corporate) & the names at our new business partner. Can I

> put on a second

> forwarder statement on my local DNS server that will effectively say,

> "if

> you can't resolve it yourself, try the corporate DNS, if you can't

> resolve

> it there, try the partner DNS?".

>

> Mr. DNS says that conditional forwarding of BIND 8.2 will do it. I'm

> pretty new to DNS. Can someone please advise.

>

> TIA

>

> Dave

>

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