ARE YOU POINTING TO THE RIGHT DNS
There's nothing easier than setting up your VIO
servers and AIX LPARs to point to the right DNS servers. Yes,
I know what you're
- You don't say “DNS Servers”. That's redundant. You just say “DNS”.
- Why should you point to a badly configured DNS? It could bring your system
to its knees (metaphorically) and you to your knees (literally).
Regarding the abovementioned point 1, I have been (self-)diagnosed with a
mild case of RAS
syndrome. I'm receiving treatment for it with the help of the internet.
As for point 2, if you don't have responsibility for the DNS, you can at
least find out who does, and ask what name servers they'd like you to use. You can hardly blame others if you're referring to a name server which was retired when your Grandma was just learning to read. On the other hand, if you correctly point to that other guy's name servers and performance heads south after that, you've got no one to blame but Someone Else. Isn't that where you want to be?
Checking the DNS you
Domain name servers, and domain names, seem to have a very short shelf life.
Chances are the first LPARs you built are pointing to DNS (I won't say DNS
Servers) which have long since shuffled off this mortal coil. You'll need to
check you're pointing to the latest valid name servers, both on the VIOS and the
DNS from the VIO server
You can list the name servers and domain that your VIO servers are
pointing to using the VIOS command cfgnamesrv.
the -ls flag to list:, as the command documentation explains:
# cfgnamesrv -ls
name server 18.104.22.168
add a name server using (you guessed it) -add
To add a name server entry with IP address 22.214.171.124,
cfgnamesrv -add -ipaddr 126.96.36.199
And it's -rm to remove an entry. Use -ipaddr to remove a name server
or –domain to remove the domain. There's also a -ch option which lets you change the domain, rather than delete the old and add the new.
Shell escape: make peace with the VIO
Allow me a little aside about VIO server commands.
I know you could edit /etc/resolv.conf
(note, there's no "e' at the end of resolv) which contains the list of name servers you
want to use. Still, it's really worth learning a few of the VIO server commands
with their syntax. Sure, they're a bit longer than AIX, and slightly different
from AIX commands, which can be frustrating, but there is a remarkable
consistency and guessability to the VIO commands in the restricted
shell (the one with padmin permissions).
- List is done using –ls
- Delete (remove) uses -rm
are referred to with -dev
- Adding entries is generally done
and so on.
Of course, you could always edit /etc/resolv.conf. After all, it’s a
short and simple file. But many other files are not so simple, so it is
learning the small subset of VIO server commands which are written
to save you remembering the format of all the files you need to
What about AIX and editing
AIX has its own command to change name servers: namerslv.
Its syntax is slightly different to that of the VIOS cfgnamesrv command. Look it up. Or you could edit /etc/resolv.conf, and I expect that's how you'll go about it. For that matter, you can use SMIT and get through to the network menus to list, add or delete name servers and domains that way.
LED 581 during boot
If your system appears to hang at LED 581 during a system reboot, chances are
it's having trouble connecting to the DNS server (there I go again) in
/etc/resolv.conf. There is an IBM technote regarding Understanding
LED 581. Although the technote was written for AIX 4 and 5, I expect it's
still valid for AIX 6 and 7. To tell you the truth I haven't read the whole
document. I'm a little busy giving myself some therapy for my newly discovered