Subnet mask?

[Kelvin Lai]

Can someone tell me why in a class C network you cannot have a subnet mask of 255.255.255.128 in HPUX but in Windows98 you can?

[Printaporn_1 · Accepted solution]

Hi Kelvin,

Because HP follow rfc1122.
To bypass RFC-1122 address checking, set the ip_check_subnet_addr variable
to zero. To make this a permanent setting, include this setting in
the /etc/rc.config.d/nddconf file.

rfc1122 is not allow each network field to be all 1 or all 0.