DNS/DHCP Outages

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I had my server freeze this evening, taking my DNS and DHCP offline for a while. In resolving it, it led me to a question. I know i've asked questions about this stuff before (i never can seem to get my head around it).

Whilst the system was down i noticed some things happening. I was unable to navigate to any websites, but online resources already in place operated without issue (ie msn, yahoo, WoW). I seemed to be able to navigate to another machine by IP, but renewing the IP killed the system.

Now im pretty sure i understand by DHCP operated in the manner it did, but correct me if im wrong:

When you obtain your Lease, it lasts for a certain period of time (say 7 days). once you have your lease, the system just periodically checks for a network connection to the dhcp server (such as when you reconnect to the network, bootup, etc), so its only really when the lease expires that you notice major issues if an outage occurs whilst you are working.

DNS im a bit confused about. it seems that your programs only need the DNS server functioning in order to establish the connection. once its running, it doesnt appear to require DNS. This seems contrary to what i would believe would happen. Surely whenever you try to communicate with the network resource. no?

Im confused.

 

Yup and don't forget that if the client can't contact a DHCP server it will not keep the lease even if it hasn't expired - W2K and XP will assign themselves an APIPA address 169.254.x.x and keep trying to contact a DHCP server every five minutes. This will break connectivity with just about everything on the subnet except other APIPA clients.

 

I tried that, all i got was

Could not display the DNS Resolver Cache.

 

Ferg, make sure your "DNS client" service is running.

 

that sorted it. should i have it running as standard? what benefit/effect will it have on the system?

 

Yes it should start automatically I believe.

The benefits are that it should in theory speed up DNS resolution as the client will check it's cache before going out on the wire to contact a DNS server.