Bind vs GTM DNS

Hello,

 

 

Any help please on this topic please ?

 

 

BR

Here is a short answer on the resolution process on GTM.

 

 

All DNS requests will come into the GTM device on port 53. There is a object created on the GTM called a "Listener" that is a self-ip address that will process DNS requests. When the DNS request comes into the Listener, GTMD first tries to match it against a Wide-IP first, if there is not a Wide-IP that matches the FQDN, then the DNS request will get dropped to BIND. If there is no match on a zone file, then no resolution will occur.

 

 

ZoneRunner is used to manage the zone files, and the daemon for that is zrd.

 

 

Hope this helps.

 

 

Chris

Hello,

 

 

Thanks for your feedback.

 

 

But is the information stored on Bind zone files and GTM Listner synchronous ?

 

 

I mean if a check or monitor detect that an IP is not valid, will the Bind zone file be updated also or only GTM database ?

 

 

BR

If a Virtual Server IP is not valid because of failing a health monitor gtmd will not resolve to that address nor will it update a BIND/ZRD zone file

 

 

Which means it is impossible to set a machine as secondary DNS server for GTM with DNS zone transfert of only valid IP adresses.

 

 

Cause only Bind support the zone transfert not Listners

You are correct that the secondary name server that you setup will only receive the BIND zone file. You would not want the zone that you have wide-ips created for to be on a secondary non-gtm name server because if someone queries that server they will not get the global load balancing benefit for the records you want globally load balanced.

 

 

What you may want to consider is to delegate a subdomain ie gtm.domain.com to the listener address and have your wide-ips be in that domain.

 

 

ie:

 

configure a wideip www.gtm.domain.com

 

 

In the zone file domain.com

 

 

gtm.domain.com. IN NS gtmlistener.domain.com.

 

gtmlistener.domain.com. IN A 1.2.3.4

 

 

 

www.domain.com. IN CNAME www.gtm.domain.com.

 

 

 

By doing this you can have your domain.com. zone file always delgate the www.domain.com queries to the wideip on the gtm even if the user query hits a secondary name server.

 

 

This is a common practice when organizations want to keep their domains on a separate name server from GTM but still get the benefit of global load balancing for that zone.

 

 

Let me know if you have more questions.

 

 

Chris

Hi

 

 

Thanks for your feedback.

 

 

What I am looking for is to set:

 

 

- 10 linux machines that need to talk to 100 routers (grouped as routers.domain.com)

 

- routers are monitored via a sip healthcheck via GTM

 

- Define linux machines as seconady DNS to save bandwith and avoir network outage => this implies request a zone transfert to GTM box

 

 

Is it possible with your hint ? means:

 

 

- configure a wideip groupping the routers with associated monitors

 

- define a bind zone file called routers.domain.com delegated to listner

 

 

Thanks for ur help

 

 

BR

Ok. If I understand correctly, this is what I think you need:

1. Delegate a subdomain in your zone called rtr.domain.com and delegate it to your listener address of your GTM.

rtr.domain.com. IN NS gtm.domain.com.
gtm.domain.com. IN A  1.2.3.4

2. Create a CNAME record that aliases routers.domain.com to routers.rtr.domain.com.

routers.domain.com. IN CNAME routers.rtr.domain.com.

3. Create a GTM Pool that has your 100 routers in it.

4. Create a Wide-IP called routers.rtr.domain.com that contains the GTM Pool with the 100 routers.

5. Set your Linux machines up as secondary name servers of domain.com.

Now with that said, here is what you have when this is complete:

- Linux machine has a copy of the domain.com.

- Linux machine will look to itself for routers.domain.com and be sent to the alias of routers.rtr.domain.com.

- Linux machine will send request for routers.rtr.domain.com to the GTM listener address.

- GTM will process the request for routers.rtr.domain.com according to how you have configured your Wide-IP.

Let me know if this helps you out or if you need more assistance.

Chris

Hello,

 

 

But what we are lokking for is to provide the secondary DNS (Linux boxes) with valid valid zone "routers".

 

 

I think with the configuration you have proposed: Linux will trigger it DNS => Routed to GTM bind => Delegation of the zone to GTM listner => Wideip => Result.

 

 

The result will not be a zone but only One or multiple IPs (A records).

 

 

So no zone transfert is happening

 

 

BR

Hi,

 

 

Do we need to setup GTM as DNS server for sub-domain in this case or no DNS config required in GTM ?

 

 

Regards

 

RK