AIX 5L Problem Determination - IBM Redbooks

► The host must be reached by a distant gateway (a gateway that is on a
different autonomous system than the source host). The RIP can be used
only among hosts on the same autonomous system.
If you are using dynamic routing, you should not attempt to add static routes to
the routing table using the route command.
As a very last resort, you may flush the routing table using the route -f
command, which will cause all the routes to be removed and eventually replaced
by the routing daemons. Since any networking that was functioning before will be
temporarily cut off once the routes are removed, be sure no other users will be
affected by this.
If your system is going to be configured as a router (it has two or more network
interfaces), then it needs to be enabled as a router by the no command. The
network option that controls routing from one network to another is ipforwarding
and by default is disabled. To enable it, enter:
# no -o ipforwarding=1
This is not a permanent setting and after the next system reboot it will be lost. To
make this permanent, add this command to the end of the /etc/rc.net file.
Note: When you add the second network interface to your system, a new
entry will appear in the routing table. This is a route associated with the new
interface.
8.3 Name resolution problems
If network connections seem inexplicably slow sometimes but fast at other times,
it is a good idea to check the name resolution configuration for your system. Do a
basic diagnostic for name resolving. You can use either the host command or
the nslookup command.
# host dhcp240.itsc.austin.ibm.com
dhcp240.itsc.austin.ibm.com is 9.3.240.2
The name resolution can be served through either a remote DNS server or a
remote NIS server. If one of them is down, you may have to wait until TCP
timeout occurs. The name can be resolved by an alternate source, which can be
a secondary name server or the local /etc/hosts file.
First check the /etc/netsvc.conf file and the NSORDER environment variable for
your particular name resolution ordering. The NSORDER variable overrides the
hosts settings in the /etc/netsvc.conf file. Check the /etc/resolv.conf file for the IP
Chapter 8. Network problem determination 185