Primary and Secondary DNS

[Deepseadata]

Hey there,

This HAS to be a pretty common scenario.

I have a 2801 as a gateway to my satellite internet and my DHCP server. I have an SBS server that I want to use as my DNS server because, from what I've heard, it will save bandwidth. The problem is that when/if my SBS goes down I want to be able to use my router as the DNS server.

My friend told me that there's a good chance that when the SBS goes down, the clients won't be able to browse the internet because they didn't automatically switch over to the secondary (router) DNS entry.

Is that true?

Here's something I just read about dns... if you're bored.

http://www.nil.si/ipcorner/RouterDNS/

 

[burtsbees]

That's not necessarily true---when a DNS srver goes down, the request is made for a resolution to the IP address...after a certain time limit and no answer, it tries the secondary. That's the entire purpose of a secondary DNS server.

Burt

 

[Deepseadata]

Thanks Burt,

Are all the timing adjustments all done in the DNS-view?

Is there a rule of thumb for setting the parameters up?

Should I use the router as the primary DNS or the Small Biz Server?

The problem is that I'm working with a guy that knows SBS's really well but knows nothing about Cisco and WAN situations.

 

[burtsbees]

Well, the only thing here is really is that if you have a guy that knows SBS, then just make that the primary. If the router separates networks, like the DHCP server network from hosts that utilize dhcp, then you must have an ip helper-address (that of the dhcp server) configured in the router to forward dhcp broadcasts/unicasts to the clients.

router(config)#ip helper-address x.x.x.x
x.x.x.x=dhcp server
If all clients can get to the router, then they will be able to get dhcp addresses from the router in case the SBS server goes down.

Burt