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Subnet mask

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by Member 26962261 1 view

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We have some Windows 98 station. Sometime when we reboot the pc the subnet mask change without any reason. Our DHCP push 255.255.252.0 and on the Windows 98 station they it goes to 255.0.0.0. . So some network software stop working. The only workaround I found at this moment is to release/renew the IP address with winipcfg. We don?t have this issue on other Operating system (nt, 2000, xp). Thank you for your help.

9 replies

by sgt_shultz

hmmm, sounds like it is having trouble finding the dhcp server at boot time...one thing that is easy i would try: see if the nic on the win98 box is set to 'autosense' media type. lock it down to 10mb half duplex for a test, see if it fixes the problem...

by Member 26962261

Thanks but that doesn't help me because I can't go 10mb. Also this problem is not constant(approx twice a week). So sometimes it's working sometimes not. Thanks again.

by pesk, mbcs, mcse, mcitp, sts

It would appear that the DHCP server is trying to supernet the subnet mask. As you may know, the type of subnet mask you are using is class c which gives you the following information;
255.255.252.0:22=62subnets, 1022hosts, 63364 total nets and hosts.
If the DHCP server is not releasing some addresses (which is sometimes common and as such you have to do it manually) it may be running out of addresses and thus tries to supernet so as to save the IP pool. I qould give the Win9x sets all staticIP's and subnet masks and remove these from the DHCP's IP assignment pool.

by Member 26962261

Thanks for your help. But the problem is only on Windows 98 station. So the problem doesn't came from the DHCP. Static IP is the easiest solution but we don't want that(for now). Thank you.

by ctmoore1998

Depending on what OS your DHCP server is - go to microsoft and do a search on Jetpack.exe this util is can be used to compact and verify the DHCP database. Running it may correct the problem. Try it after trying the fixed media type. Go into the adapter properties in network neighborhood and advance tab of the properties and find the media type/speed option change from auto or default to 100 half and try that for a week or 2 if problem persists try the jetpack util

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