DHCP and 2 subnets

Simon Hobson dhcp1 at thehobsons.co.uk
Sat Apr 12 17:27:58 UTC 2008

Chris Arnold wrote:

>Well, it is with much thanks to you all on the dhcp list that i 
>energetically tell you that this works now :))

Another satisfied customer.

>The only thing i have noticed is on clients on the 123 network, it 
>takes a long time to get an IP (like minutes); longer than clients 
>on the 124 network. Is there any reason you can think of when 
>looking at the config:

No, what do the logs show ? That is always the first place to look !

There are many reasons why a client might not get a lease straight 
away, but usually the logs will show why. By now you should be 
familiar with the Discover-Offer-Request-Ack cycle of messages, so 
you are looking for log entries that are different to this.

>On the dns updating side----i have searched the archives of the list 
>and read the man pages and see where there is only 2 ways and 1 does 
>not work (ad-hock). So you can see from the config file i have 
>interim; but i still am unable to ping a dhcp client. Any ideas on 

As Glenn says, see the config examples. You can allow updates by IP 
address, but normally you would use a key to sign updates, and for 
this you need zone declarations in your DHCP config (which I see you 
don't have). The default for BIND is to not allow any updates, so any 
attempts will fail. Again, the logs are your friend - both the DHCP 
server and the BIND server.

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