Subnet mask change 1

[ltromans]

We had outside assistance to rebuild our server when we lost a couple of drives, and somehow, during the rebuild, the subnet mask changed from 255.255.0.0 to 255.0.0.0
I would like to change it back. Can I? Should I? None of my ip addresses have changed - all my devices have static ips (except the pc's), and all are working properly. I found all kinds of stuff about changing ip's , but not the mask.
Thanks
Leslie

 

[goombawaho]

You should change it back to whatever it was before all the chass.

INETCFG is the tool to do it.
Protocols
TCP/IP

See this document for a picture.

http://www.more.net/technical/netserv/tcpip/viewip.html

 

[marvhuffaker]

It's not a big deal to change it back. Should be able to do it live without even bouncing the server.

Marvin Huffaker, MCNE
Marvin Huffaker Consulting, Inc.
A Novell Platinum Partner

http://www.redjuju.com

 

[ltromans]

I went into inetcfg and in the TCP/IP Protocol Configuration screen, and I did not find ANY reference to the subnet mask. In the Bindings section, both instances of TCP/IP showed the subnet mask of the connected network as FF.FF.0.0. In the View Configruation section, under All INTCFG commands, it shows the following:

BIND IP N100_1_E82_EII ARP=Yes Mask=FF.FF.0.0 Address=XXX.XXX.XXX.XXX
BIND IP N100_1_EII_EII ARP=Yes Mask=255.255.0.0 Address=XXX.XXX.XXX.XXX
(The address listed is the server address)

Typing “config” at the server console shows the correct mask.

Typing ipconfig at the pc level, shows the mask as 255.0.0.0 .

In theDNSDHCP utility, DHCP service, Addressing tab, the mask shows 255.255.0.0, but the “Other DHCP options” show the subnet mask to be 255.0.0.0. An attempt to change the mask here, results in an error “EDHCP131 : Mask range must be larger than the mask range defined in the subnet.

So apparently, the only issue is the mask in the DHCP section which governs the subnet for the pc workstations. The lease type is timed and set for every 3 days.

Should I worry about this or leave well enough alone?

 

[goombawaho]

FF.FF.FF.0 = 255.255.255.0

Look here for where to find the exact spot to make the change.

http://www.unoverica.com/documentation/ucm/mt211b14.html

http://www.unoverica.com/documentation/ucm/mt211b18.html

 

[marvhuffaker]

You shouldn't specify the subnet mask in the DHCP options. It should give it out automatically. I would just remove the option from that screen. I have never seen a situation where I had to include that option anyway.

Marvin Huffaker, MCNE
Marvin Huffaker Consulting, Inc.
A Novell Platinum Partner

http://www.redjuju.com

 

[ltromans]

Thanks Marvin

I removed the option in the DHCP Service and it immediately changed the subnet mask in the dhcpsub addressing section to the correct one (255.255.0.0). Heowever, even after releasing the lease, deleting the ip address and then logging back in, my test pc still shows a subnet mask of 255.0.0.0

Will this change flow down to the pc's over time or on the next server reboot?

 

[marvhuffaker]

DHCP needs to be restarted before a change will be handed to clients.

Just do this:

UNLOAD DHCPSRVR
LOAD DHCPSRVR

Should be golden. You could also reboot the whole server, the point being that the DHCP service needs to reload the configuration.

Marvin Huffaker, MCNE
Marvin Huffaker Consulting, Inc.
A Novell Platinum Partner

http://www.redjuju.com

 

[ltromans]

Thanks again Marvin
That did the trick.
Leslie