ipconfig/release

Release all DYNAMIC settings. So not the static IP address etc. but it does release the DHCP assigned stuff.
Contrary to a /renew, it will not do an attempt to contact the DHCP server to renew existing address 'leases'. But with most standard card settings, it will send a broadcast for DHCP as if it were a brand new workstation. So in many cases, /release leads to being given a new IP address while /renew leads to getting back the existing one (with a longer remaining lease period of course, usually being 72 hours).

At your service,

- The Netherlands

ipconfig /release (usually followed with the designated network adapter you would like to release the address for) is used to release the current IP address the DHCP server has given it. It will not wait for the lease period, because you are manually terminating the lease. Just be sure your DHCP server is up and running before you do it, so when you go to renew the address lease, it will have something to assign the new address with. Hope that helps.

is this your ISP?? or your own Network?

if it's your ISP, most have a very short TTL [some are 4 hours long] and if you send a DHCPrelase message at or near the 50% lease period, chances are the ISP DHCP server will delete your IP entry. If you send a DHCPrenew message shortly there after, you'll get a new IP address.