One dhcp server multiple DNS

Simon Hobson dhcp1 at
Wed May 21 09:29:12 UTC 2008

Suhaime Raeze wrote:

>I have this situation I have two DNS server one for internal use 
>another for external access. I have users which can bypass the proxy 
>and using the IM such gtalk and yahoo messenger. Question is: Can I 
>have two set of dhcp settings in one server? One settings pointing 
>to internal DNS and another pointing to external DNS. Without 
>external access I can block the usage of IM in my environment

Sorry, I just don't understand that question !

What do you mean by "two set of dhcp settings" ?

Do you mean give different settings to different clients ? The answer 
to that is yes, but you need to define what you want given to what.

If you want to prevent users bypassing your proxy etc, then the way 
to do that is to block outbound access to DNS servers other than your 
own official ones. Once you do that, then you can control what the 
DNS hands out. But don't forget that people can bypass that by 
entering an IP address instead of a hostname.

In general, if you want to control something like that, the firewall 
is the place to do it (or policies on the desktops) - DHCP is not a 
security tool and can be easily bypassed.

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