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What tools are available for allocating and tracking which addresses are being used? Specifically, our issue is that sometimes an IP is taken for a VM and when we go to build new ones they're not necessarily up for the quick 'n dirty "ping test".

Right now there's a Google Spreadsheet, but inevitably we forget to update it.

It has to be shared and easy to update.

Should I just bite the bullet and go with a DHCP server?

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up vote 13 down vote accepted

You should setup a DHCP server, and then keep a spreadsheet or table in a doc of any static addresses you manually set. We have a page in our documentation wiki, but a Google spreadsheet should be good too.

Is there something you have against a DHCP server? I tend to believe that DHCP pretty much always makes my job easier and I try to use it whenever possible. If you want computers to reliably get the same address setup reservations.

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In my experience it's simpler just to give all servers statics and be done with it. Servers - static. Clients - DHCP. Nice and simple. – PowerApp101 May 22 '09 at 2:32
Seconded Zoredache - use DHCP for everything, even servers. Give the servers static mappings (their MAC always gets the same IP) and you get the best of both worlds. And when you need to renumber you don't have to change every fscking server, you just change the DHCP server config. – pjz May 22 '09 at 2:58
We agree to differ :-) – PowerApp101 May 22 '09 at 3:20
I third Zoredache. Also second pjz's idea of giving servers static DHCP leases. – Orihara May 22 '09 at 3:52
The big downside to having your servers on DHCP is it adds another dependency (the DHCP server(s) must be the first to boot), and a point of failure (the DHCP service). – derobert May 22 '09 at 4:50

In my experience what works best is the Master IP Spreadsheet to Rule All Others. That is, there exists one spreadsheet and it is everyone's responsibility to update it. If it ain't in the spreadsheet, it ain't live. No ifs no buts. People soon learn to update it. Also, I wouldn't use DHCP for any servers, even test ones. The last thing you want on a server is the chance that it's IP might change.

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+1. Now we can have a flamewar as whether the format of the master spreadsheet should be XML, SQL, Excel :-) – bortzmeyer May 22 '09 at 6:13
No flamewar necessary, Excel is the correct answer ;-p – PowerApp101 May 22 '09 at 6:18
The best format is whiteboard or glass wall! – icelava Jun 3 '09 at 9:58
As noted above, you can configure the DHCP server to hand out the same IP address to the same MAC address every time: a static address, in other words. Thus, the server's IP never changes - even though it received the IP address via DHCP. – Mei Jun 18 '09 at 2:20

We use our documentation wiki, and map out all of our subnets in tables. If an IP is used, the documentation is updated. Now it's gotten to the point that we don't know what IPs we have available unless we consult the documentation, and thus we end up updating it. Besides, one or two IP conflicts with production equipment generally sets people straight.

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Every one of our servers has DNS, so I just check the DNS records for free IPs everytime I need to assign a new static IP to a piece of hardware. I don't see any need to record this data in multiple places.

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This is what I do also – Kevin Kuphal Jun 3 '09 at 15:47


That is all.

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i'm happy user of ipplan to manage multiple subnets. some of them do use DHCP - mainly networks for workstations, while other have manual configuration.

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We manage our DNS/NIS hosts via an LDAP OU which in turn is used to build DNS, DHCP and the NIS hosts map dynamically every 10 minutes. This has been very useful as we have over 30 admins updating records on a daily basis.

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If you have an environment where next to the static, wellknown ip's there are also a bunch of workstations, clients, (test)servers getting their ip from a DHCP server, or simply using a static IP for the duration of the test or what not (which is the case here where I work right now) you could try looking at programs like Look@LAN which scans the entire IP range and shows hostnames etc.

While it's not exactly bugfree, it does the job. There's probably hundreds of other software packages out there, but they had this one installed when I arrived so I just keep using that for the time being. It gets the job done so what more would I need?

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