HPUX conforms to the RFC-1122 guidelines on IP's and Subnetting. This RFC will not allow you to assign an IP address to an interface from the zero subnet i.e. x.x.x.0. (x=non zero value).If you attemp this you are using a IP Address/Subnet Mask that violates RFC-1122 and this address will not appear in the table if you issue nstat -rn, you will only see the loop back address 127.0.0.0. There is a variable that can be changed which disables the checking for conformance to the RFC. The only resolution is to disable the IP/Subnet conformance incorporated into the HPUX platform or set the interface manually by putting a script in /sbin/rc2.d simply name it starting with a "S". e.g. "Setlan" When using ip schemes that do not conform to RFC-1122 there is a variable that can be changed which disables the checking for conformance to the RFC. RESOLUTION Issue the following command on HP-UX 11.0: ndd -h unsupported | more The variable ip_check_subnet_addr - Controls the subnet portion of a host address 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. Summary: The following output is what is seen if you are checking subnets: # ndd -get /dev/ip ip_check_subnet_addr 1 Set value # ndd -set /dev/ip ip_check_subnet_addr 0 Now reread the netconf and nddconf files: # /sbin/init.d/net start To make this permanent edit /etc/rc.config.d/nddconf and add a set of lines: TRANSPORT_NAME[0]=ip NDD_NAME[0]=ip_check_subnet_addr NDD_VALUE[0]=0 Also add the line, "/usr/bin/ndd -c" after the line "usr/bin/ndd -a" in the /sbin/init.d/net.init script. On HP-UX 10.20: With HP-UX 10.20 use the nettune command to make this change /usr/contrib/bin/nettune -s ip_check_subnet_addr 0 To make the change permanent: 1. Create a text file called nettune_script with the following line: /usr/contrib/bin/nettune -s ip_check_subnet_addr 0 2. mv nettune_script /sbin/init.d/nettune_script 3. chmod 555 /sbin/init.d/nettune_script 4. chgrp bin /sbin/init.d/nettune_script 5. chown bin /sbin/init.d/nettune_script 6. cd /sbin/rc2.d 7. ln -s /sbin/init.d/nettune_script /sbin/rc2.d/S006subnet -Contributed by Corey Harris