DHCP not working properly

[featured_spectre]

Good afternoon all. I have just come across a gem of a problem for anyone who has a good technical mind.

 

On our DHCP, it farms out the addresses as you would expect, however it does not change the name that is with the IP address. For example my 1st IP with DHCP was 10.9.25.5 and my PC name joined that IP. At the minute, my IP current address is 10.9.25.93 however even after clearing the cache, and the full server list for DHCP IP addresses, it is still saying on the server that my PC is bound to the IP 10.9.25.5

 

Does anyone have any thoughts on how to fix this as this is a problem as we cant see who has what IP on the server!

 

Thanks

 

Carl

[Mcshammer_dj]

have you cleared the dns totally both client cache and on the server

[featured_spectre]

yes, that was the first thing I did and there was no joy, short of turning it off and going to static IP (which I hate doing!) I havent been able to figure a way around this

[Mcshammer_dj]

use mac address filtering within DHCP to ensure that the same IP is applied to the same machine

[OutToLunch]

How long are your leases set for?

[featured_spectre]

thing is because so many people come and go in our school (supply teacher wise and consultants etc) who require the internet, doing mac address filtering would screw us up as we would run out of IPs in a VERY short amount of time, and my bosses made it abundantly clear they only want 1 IP range (10.9.25.xyz) for the adults to keep things easier. God knows why!

 

Oh and leases are set for 12 hours, it was 8 days however we found that we ran out of IPs, so having it down to 12 hours made it easier in terms of farming the IP addresses.

[OutToLunch]

I'm not an MCSE type so will happily stand corrected, but I'd look at changing the refresh interval on your server for DNS/DHCP.

 

How DNS dynamic updates work together with the DNS "aging and scavenging" process in Windows 2000 and in Windows Server 2003

How to configure DNS dynamic updates in Windows Server 2003

DatabaseCleanupInterval

[featured_spectre]

I have done that also, changed it from all sorts of ranges from 1 hour to 3 days to 1 week, still no luck, even our covercard engineers are baffled.

[User3204]

I'd increase the range.... I know you've been told not to, but...

Our LA gave us one /24 range for the staff network, which comprises of:

6 servers

20 printers

55 desktops

120 laptops

15 manages switches (roughly, okay so these could have gone elsewhere).

You can squeeze that in, but it'll be tight, and there's no room for expansion.

 

How many machines are you trying to push into those 255 addresses ?

DNS caches these things for longer that DHCP does, I dunno where it is set. Something about "scavenge old records" or something, and I have a feeling you have to set it more than once.. or am I confusing myself with WINS ?

[featured_spectre]

in a working week we can have upto 300 seperate people who require access, however not all at the same time, which is why we had it cut down to only a few hours.

[Earthling]

and my bosses made it abundantly clear they only want 1 IP range (10.9.25.xyz) for the adults to keep things easier. God knows why!

 

 

For the adults? To keep things easier?

 

You have my sincerest sympathy, if that's the standard of 'adults' you support.

 

[diggory]

If you right click on your scope (in the DHCP management console) you can get an overview of how many IP addresses you have free with the stats option.

 

It might be worth checking that the credentials for the server are up to date.

 

Right click on the DHCP server, go to the advanced tab (why are most useful things there...), then the 'Credentials' button.

 

It should have the settings for a user (who has the access rights) to update each machines registration on the DNS when it gets a new dynamic IP address.

(Which sounds a bit like your problem).

 

We've got admin in there - but you could use a user who has appropriate DNS rights for more security ... I think

Edited May 13, 2009 by diggory