Times Matching on DHCP Clients and Servers

• Microsoft Windows NT Server versions 3.5, 3.51, 4.0

SYMPTOMS

When you view the active leases on your Dynamic host configuration protocol (DHCP) server in DHCP Manager some of the client leases may be unavailable (grayed out).

CAUSE

The DHCP server's clock has been advanced so that it considers these leases expired.

RESOLUTION

To resolve this issue, you will need to perform the following:

1. Verify that the clock times on the DHCP server and clients are correct for their location, taking into consideration time zones.



2. Renew the affected clients' IP leases:
   
   Windows NT
   ----------
   
   Type the following at a command prompt and press enter:
   
   ipconfig /renew
   
   Windows 95
   ----------
   
   Start Winipcfg.exe and click Renew all.

MORE INFORMATION

When a DHCP server leases an address to a client, it sends a lease duration. The client then knows that the lease expires at CurrentTime + LeaseDuration. The DHCP server also sets the active lease with CurrentTime + LeaseDuration. If the date or time on the server advances for any reason it may prematurely age the leases that it maintains.

For example, if a DHCP server hands out a lease at Noon and then the time on the DHCP server is adjusted three hours ahead it has the same effect as the lease aging three hours as far as the server is concerned. There is no communication to the DHCP clients about the change.

Keywords : kbnetwork nttcp NTSrv
Version : 3.5 3.51 4.0
Platform : winnt
Issue type :