[ubuntu-us-mi] name resolution issue on Lucid

[Robert Citek]

I'm just curious to know if anyone else has seen something similar
with name resolution.

In this current network setup there are three machines that I'm working on:

1) a RHEL machine running BIND (9.2.4), IP address is 10.1.1.1
2) a CentOS machine
3) a Lucid machine

For simplicity the zone file on the RHEL machine looks something like this:
www A 10.1.1.10
foo A 10.1.1.11
bar A 10.1.1.12

I needed to change the bar address to be the same as www. Before I
did so I ran dig on all three machines against BIND on the RHEL
machine to be sure that bar returned x.12:

$ dig @10.1.1.1 bar +short
10.1.1.12

I then changed the entry for bar to this:

bar CNAME www

and reloaded BIND.

When I reran the dig, dig returned the new IP address for bar on the
RHEL and CentOS machines

$ dig @10.1.1.1 bar +short
www
10.1.1.10

but on the Lucid machine, dig returned the old IP address:

$ dig @10.1.1.1 bar +short
10.1.1.12

I checked this several times on Lucid and kept getting the old IP.
What's interesting is that I get the same result using host. Here it
is on RHEL and CentOS:

$ host bar 10.1.1.1
Using domain server:
Name: 10.1.1.1
Address: 10.1.1.1#53
Aliases:

bar is an alias for www.
www has address 10.1.1.10

And on Lucid, host returns the old IP:

$ host bar 10.1.1.1
Using domain server:
Name: 10.1.1.1
Address: 10.1.1.1#53
Aliases:

bar has address 10.1.1.12

It seems as though Lucid is doing some kind of caching. Does this
look familiar to anyone?

Regards,
- Robert

[Scott Moser]

On Jul 14, 2010, at 12:08 PM, Robert Citek <robert.citek at gmail.com>

Post by Robert Citek
10.1.1.12
I checked this several times on Lucid and kept getting the old IP.
What's interesting is that I get the same result using host. Here it
$ host bar 10.1.1.1
Name: 10.1.1.1
Address: 10.1.1.1#53
bar is an alias for www.
www has address 10.1.1.10
$ host bar 10.1.1.1
Name: 10.1.1.1
Address: 10.1.1.1#53
bar has address 10.1.1.12
It seems as though Lucid is doing some kind of caching. Does this
look familiar to anyone?

Both dig and host (with explicit nameserver) should be doing a network
request rather than a getaddrinfo (or similar). Thus there shouldn't
be any caching there.
I really don't have an idea. I'd next try packet sniffing to see
what's going on.

[Robert Citek]

Post by Scott Moser

It seems as though Lucid is doing some kind of caching. ?Does this
look familiar to anyone?

Both dig and host (with explicit nameserver) should be doing a network
request rather than a getaddrinfo (or similar). Thus there shouldn't
be any caching there.

That's what I would think

Post by Scott Moser
I really don't have an idea. I'd next try packet sniffing to see
what's going on.

Rebooted the Lucid machine and all's well. Seems very odd. I'll be
doing some more changes soon. If I see it again, I'll fire up
wireshark as I'm not too keep on rebooting my machine every time I
want to see a change in DNS.

Regards,
- Robert