I got 500 computers on a network using dynamic ip addressing by DHCP operating at class B (255.255.0.0). Each 4 computers are connected to a switch. The network oftenly experiencing subnet mask clashes that is the subnet mask automatically changes from class B to class A(255.0.0.0). anyone ever experienced this problem? any concrete solution or reason why this abnormal situation oftenly occur on my network?
2006-08-01 18:38:27 · 4 answers · asked by Infinity 1 in Computers & Internet ➔ Computer Networking
to resolve this problem you can apply static ip address resolution in DHCP itself or you can break your network in subnets of same class 'B' Subnet masks.
2006-08-01 18:53:21 · answer #1 · answered by waytospark 2 · 0⤊ 0⤋
It sounds like you have another DHCP server on your network that is set to serve the same range of ip addresses with a different subnet mask. Once a workstation has obtained its IP address and subnet mask, it does not change "automagically" unless it needs to be renewed.
Check the IP statistics of one of the offending workstations by opening a command window (Start > Run> cmd) and typing ipconfig /all in the command window.
The address of the DHCP server will be in that output. Check that DHCP server against the DHCP server of a good workstation. If the server addresses are the same, check the IP properties of the workstation with the wrong subnet mask (Start > Control Panel > Network Connections - then right-click on the Local Area Connection, choose Properties, choose IP Protocol, click Properties, and see if the subnet mask is set incorrectly in that window)
2006-08-01 19:54:20 · answer #2 · answered by airwrck 1 · 0⤊ 0⤋
Someone has probably set up an unauthorized DHCP server on your network, somewhere among those 500 computers. Probably it is a Windows 2003 server that they are wanting to get experience with, and they have enabled the DHCP server on it. (But it could be a Linux server or some other type, too, even a Cisco router with DHCP enabled.) To find out, set up a network sniffer to track DHCP traffic, and look for DHCP responses that do not come from your normal server.
2006-08-01 19:43:48 · answer #3 · answered by DadOnline 6 · 0⤊ 0⤋
in addition to everything that everyone has said, CLASSES are depricated. the correct terms are /8 /16 /24 and /32, with others in between
2006-08-01 20:08:46 · answer #4 · answered by duct_tape_is_good 4 · 0⤊ 0⤋