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I used to use Amahi, and Amahi by default has a built-in DHCP and DNS servers switched on.

Now, I removed Amahi, and am assembling my own home server using Ubuntu server.

My setup: an ADSL modem / WiFi router, a server connected to it with Ethernet cable, and a number of clients (from 2 to 5 normally) connecting over WiFi.

The router has built-in DHCP, and I normally use some external (not ISP's) DNS addresses, like Google's or OpenDNS'.

Does it make sense setting a separate DHCP on the server machine? Setting it as a DNS cache for the LAN?

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up vote 2 down vote accepted

I don't think it makes sense to do so in this case unless there is something specific your router did not do (like as in the case of a Windows Server DNS server registering clients for internal resolution). In your case, it seems like it would be more overhead on your server (not much though), but more importantly, more to set up and administer. DHCP on these routers is pretty simple to do, after all.

Seems like extra work for nothing to me.

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I thought he meant ditching the one on the router and only having one on the server, and in that case, I was in favor of just the one: On the router. – KCotreau Aug 6 '11 at 23:40
well, ok. I expected that, but assumed I may be missing something. and what about setting th eserver as a DNS? it could cache the records and thus give some internet speed boost? and if settings dns there, dhcp should be there as well, if I'm not mistaken – Guard Aug 7 '11 at 11:51
@Guard: You don't necessarily have to setup DNS and DHCP on the same physical device. If you are happy with the router's DHCP and/or DNS services, then I would just leave it. A DNS server will speed up resolution, but it won't be a significant boost to your internet speeds unless you have a rather high latency connection to your current DNS resolvers. – surfasb Aug 7 '11 at 12:19
There is not a huge overhead with querying your DNS server for a few client computers. I would just continue to let them get the DNS settings from the router' DHCP, and let them query the DNS server on the Internet directly. – KCotreau Aug 7 '11 at 13:08
well, ok, thank you :) – Guard Aug 7 '11 at 19:27

You must not have more than one DHCP server per network segment; You may have multiple DHCP servers across multiple segments if the routers between each segment are configured to not relay DHCP requests and responses.

Having a separate DNS server on a LAN may be useful since it will allow you to supplement the upstream DNS server with responses valid only on your LAN, as well as perform caching of DNS responses.

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I'm pretty sure he meant replacing the DHCP function on the router. On another note, having more than one DHCP server on a network segment is easy. Just give them non-overlapping address pools. – surfasb Aug 7 '11 at 1:54
@surfasb, +1+1, :) – Guard Aug 7 '11 at 11:49

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