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I manage a small-ish network that consists of less than 70 nodes. The previous system administrators opted to have a dhcp server and manually set dhcp addess.

I have opted to rather use dhcp address assignment instead of static address assignment except for my domain controllers and EXS hosts. I have been critised for following this scheme, but its way easy for me to manage the address scope with out having to scan the network for available ip addresses. Am i on the right track or have i lost the plot?

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7 Answers 7

up vote 6 down vote accepted

Why were you criticised for doing it that way? I mean I think it's crazy not to use DHCP for workstations at least, but maybe there is something specific to the environment that changes that equation.

The only issue I can see with DHCP is ensuring that your scope is properly created and doesn't cross over with the pool of static addresses you use (even that can be got around with reservations but its more work than needed).

That aside, users should never ever need to know whether or not you use DHCP because their workstation should 'just work', except for when the DHCP server is not available (and if that's an issue, you just have more than one DHCP server online).

EDIT: Convict makes a good point about documentation, make sure you do have the IP address ranges documented, explaining what you've done, why and how to find it. I don't think people are comfortable with the idea that some tools are "self documenting" (and to an extent they might have a point, how would you easily re-create your DHCP database with all your reservations, if you couldn't restore from backup?).

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I too am seriously curious! What reasons were given for this criticism? –  quux Jun 10 '09 at 8:21
    
previous network admins assignment addresses in the dhcp pool to servers, without excluding those addresses. Since 95% of the computers are infact servers offering custom applications i prefer to assign these 'servers' addresses by way of dhcp reservation –  biosFF Jun 10 '09 at 8:27
    
@biosff - well the way you're doing things there certainly makes sense. I'm still boggling at the idea you'd get criticised for it, few of our users know or care about whether we use DHCP or a dartboard to assign and manage IP addresses and as long as things work they don't care either! –  RobM Jun 10 '09 at 8:49
    
The documentation is the DHCP database, IMHO. You should back it up and test restoring it. Why keep separate documentation that will fall out of date when you can use the database / config file that drives the DHCP server as the authoritative documentation? –  Evan Anderson Jun 10 '09 at 12:03
    
Evan, I'm inclined to agree but that makes people who don't understand that uncomfortable. At the very least you need to write a puff piece of documentation explaining what you've done and where to look and how to pick it all up. –  RobM Jun 10 '09 at 12:31

Yes, I think you're on the right track.

I suspect that you're being criticised because ...

  • of the lack of documentation about your network, rather than your choice of technology to assign an IP address;

  • you're doing IP address assignment differently to the way it's always been done. You're challenging the status quo.

Ask more questions to find out the real reason for the criticism. You may have to teach your detractors about DHCP and its benefits to your network administration.

People will come around to your way of configuring the network once they see how much easier it is to add another workstation to the network when the IP address is allocated by DHCP. DHCP should mean the end of those pesky duplicate IP address allocation errors that have plagued your network in the past.

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When you say the previous administrators "manually set DHCP address" do you mean static assignments?

If so, this is generally the easier way to manage pools of workstations on a LAN. Statically tie each machine's MAC address to a specific IP and deliver them by DHCP. You get the trade off of knowing exactly where each machine is and being able to change the assignments without visiting each discrete machine.

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Adding my vote to DHCP all the way. I can't understand why someone would criticise you for suggesting this, the whole point is to make it easier to manage the address scope, and as soon as you have more than 5 or so workstations, it makes sense.

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About the critics: there are still people around, that don't know DHCP with StaticIP via the MAC-Adress. They think, that DHCP = CHAOS, so you better tell em whats really in the bag.

I also can recommend different IP-ranges, something like this:

1-9 important Servers (static)
10-99 misc. Servers (static)
100-150 Sales & Marketing (DHCP with MAC)
151-200 Developers (DHCP with MAC)
200-253 Tech.Stuff (DHCP with MAC)

Another vote for DHCP is, that you can handle all IPs from one, central instance.

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Tee-hee... I remember when I "cared" what host portions of their IP address were assigned to certain kinds of computers, devices, etc. I'm glad I let go of that. (Which network portion that gets assigned matters a lot, and is related to the VLAN the host lives in. As far as host portions of IP addresses, though, I couldn't care less. I have dynamic DNS, reverse lookup zones, and DHCP reservations... the host portion of the IP address is meaningless to me.) –  Evan Anderson Jun 10 '09 at 12:05

DHCP is by far the best choice as soon as you have more than a few stations.

Static entries should be for servers and communication devices.

I use IP range:
Static .1 - .50 for servers, printers, routers, etc.
DHCP .51 - .150 for workstations

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"Static" and "DHCP" are not exclusive. It is very common to use DHCP to deliver static addresses (see mh's reply). –  bortzmeyer Jun 10 '09 at 19:58

One possible disadvantage to this is that it introduces a startup order dependancy: things which DHCP need to wait for the DHCP server to come up.

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