DHCP Setting - allocating servers a DHCP address

[speckytecky]

Apologies if this is the wrong place to post this but I have a small question which many of you will hopefull easily answer.

 

We have two DCs here and they are allocated 10.***.***.2 and 10.***.***.3 we are adding a Mini Mac server and I'd like to allocate it 10.***.***.4

 

Looking at our DHCP Scope we have 10.***.***.50 through to 10.***.***.200 with an exclusion of 10.***.***.200 to 10.***.***.210 (for switches I think). So, the actual servers are outside the scope so I can't place a reserve on the Mac address of the Mini Mac. What's the best way round this one please?

[sted]

static address/enlage the range to include server but create an exclusion range

[soveryapt]

Give servers a static address .. If you have a full DHCP range and the servers sit within that you can give them a reservation so nothing else can get that IP address, but as a rule of thumb, always give servers a static address. Just helps with problem solving later in the day if you need to.

[themightymrp]

Servers should always, ideally, have a static IP. As long as nothing else has been assigned 10.xxx.xxx.4 already then just enter it manually and document it somewhere so you don't forget!

[timzim]

Continue to exclude the range 10.*.*.1 - 10.*.*.49 from your scope so that you can use addresses from that range for static addresses as I'm sure you'll find plenty more you'll want to allocate over time. Better still include the .1 to .49 range into your scope and make it an exclusion range then there's no chance of someone else (or yourself) accidentally extending the range in the future and swallowing up those fixed IPs.

 

It's often better to give all your important infrastructure static addresses rather than reservations. If your DHCP server goes down for a few days (e.g. over a holiday) you won't have the nightmare of your servers/switches/etc losing their addresses completely once their leases expire.

Edited April 25, 2012 by timzim

[speckytecky]

Thanks for the prompt replies folks. What puzzels me is the existing servers are not listed in the DHCP reservations list so it leaves me wondering how that was done?

[soveryapt]

They are most likely on static IP addresses in that case. Or do they definitely get their IP from DHCP?

[RageRiot]

servers have to have static ip's although no doubt they will work with a dhcp address but with certain configureation and headaches when it does not work.

 

all server dependant clients work on the principal that they know where their server is.

[sonofsanta]

Thanks for the prompt replies folks. What puzzels me is the existing servers are not listed in the DHCP reservations list so it leaves me wondering how that was done?

 

If they're not in the reservations, and their addresses are outside the scope, then they are configured with a static address on each server. No reservation is needed because the address they have is outside the scope so could never be handed out anyway.

 

All servers should always be given a static address outside the scope; static for the reasons others state, and outside the scope so it's clear from the address alone that it's a server. If it was mixed in with the scope addresses then it wouldn't be obvious.

 

I also give static IPs to techie workstations because it can be handy knowing exactly what your IP is for different things (Smoothwall, FTPs etc.)

[Michael]

Sonofsanta's correct. It's recommended to have IPs available for Servers, Printers, Wireless Access Points, Routers, Switches, Admin Workstations - the list goes on.

 

So for example with a Class C range 192.168.1.1 - 192.168.1.254

 

You could specify the DHCP scope is 192.168.1.100 - 192.168.1.254, so IPs 192.168.1.1 - 192.168.1.99 can be used for anything static. Personally I still make a manual reservation within DHCP. The reason being I manage many networks, so if I or another technician introduces a device which needs a static IP, it won't create a conflict with another device.