Have MAC address - need IP address.

What OS are you using?

In NT, you can do an "arp -a" from the command prompt to look at the arp list. If the machine in question has been cached, you'll see the MAC address and corresponding IP address.

My desktop OS is Win98. I also have administrative access to NT 4.0 Servers.

I appreciate the answer of using arp -a, but it does not help if there is no entry in the arp cache for that host. I have a lot of hosts to look up. I am trying to create documentation for an undocumented network.

I can ping every ip address on the network one by one and check the arp table. I may end up doing so. Is there a more direct way? I don't want to purchase any software (such as Visio Enterprise) to do this.

Another question: do you have any Cisco routers connected to the LAN segments? If you can connect to the router, you can issue a "sh arp" command. The router will respond with both the MAC and IP address for every device directly connected to it and tell you which interface the address is being heard from. If you personally don't have access, ask the router guys to print you a copy of the router's arp table. Hope this helps.
ck

There's a great utility on zdnet..freeware.. called internet maniac. gives all kinds of conn info including arp and rarp.
address is as follows:
http://www.zdnet.com/downloads/stories/info/0,,000PJV,.html
try it out

For NT 4.0 server with DHCP service.

If you have DHCP running then in DHCP manager: Scope: Active leases you will get a list of IP addresses (plus NetBIOS names if you also have options 044 & 046 configured to link to WINS).

The Properties ofeach address includes a Unique Identifier which is the MAC address. You have to work backwards by looking at each IP address and writing or copying the MAC address manually.

One would think Microsoft would recognise the need to be able to generate such lists automatically from their Admin programs but so far they have not, although I must check Windows 2000 Server more fully.