IP Addresses

When a machine pulls an IP address, where is it stored?

I mean, if you pull an IP and then disconnect your cable and do an ipconfig, you shouldn't have an IP anymore right?

Does the nearest router store that information, like the lease, etc. and send it to the machine upon booting?

Find more posts tagged with

Save $250 on 2025 certification boot camps from Infosec!

Book now with code EOY2025

Button

Comments

Webmaster

warl0rd wrote:

I mean, if you pull an IP and then disconnect your cable and do an ipconfig, you shouldn't have an IP anymore right?

Fortunately that is not the case:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters/Interfaces/{XXXXXXXXXXXXXXXXXXXXX}

Also try a search on: DhcpIPAddress

w^rl0rd

What if the user renews the IP, then wouldn't it be 0.0.0.0?

Webmaster

On OSs different than XP: yes. XP uses APIPA (Automatic Private IP Addressing) and would assign an IP address from the network 169.254.0.0, with the subnet mask 255.255.0.0.

tokhss

depends on the client.. win9x hold on to the IP address, a release command would bring it to 169.254.x.x ... on NT clients.. if you disconnect the cable, it will search for an ip regardless and eventually
come back with 169.254.x.x (most of the time) , if not.. relase command will do the trick.

0.0.0.0 i think is when the system is hung on trying to find an IP.. correct me if i am wrong.. and windows doesnt generate its internal ip.

you beat me to it.. i thought NT in general looks for new ip, not just XP.