Subject: Network problems; no name lookups, no real connection?
To: None <>
From: Jan Danielsson <>
List: tech-net
Date: 02/02/2006 15:03:17
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Hello all,

   On a system I administrate remotely, I can no longer look up host
names. Actually, the problems seem to be bigger than that.

   First of all, there are two systems, both running NetBSD. The once
causing my grief, I'll call A, and the other one, which is physically
located 2 cm from A, I'll call B.

   A and B are connected to the internet via a cablemodem + DHCP. They
are also connected via an internal network (which I used to be able to
reach A (through B).. It has changed it's public IP, but due to the
problems I'm about to describe, that announcement never reached me).

   This is on system A:

# ping
ping: Cannot resolve "" (Host name lookup failure)

   On system B:

$ ping
PING ( 56 data bytes
64 bytes from icmp_seq=3D0 ttl=3D245 time=3D52.342 ms
64 bytes from icmp_seq=3D1 ttl=3D245 time=3D44.546 ms
64 bytes from icmp_seq=3D2 ttl=3D245 time=3D49.839 ms

   Now back to system A again; let's assume that it's only the host name
lookup that is failing:

# ping -n
PING ( 56 data bytes

   ... it just sits there doing nothing, until I break. So, obviously
we're not getting very far. Let's review the routing table on A:

# route show
Routing tables

Destination       Gateway            Flags
default        UG   link#1             U      00:b0:c2:3c:7c:00  UH          UGH          UGH
loopback          UGR
localhost          UH    link#2             U

   And try to ping A's gateway:

# ping
PING ( 56 data bytes
64 bytes from icmp_seq=3D0 ttl=3D255 time=3D33.267 ms
64 bytes from icmp_seq=3D1 ttl=3D255 time=3D32.393 ms
64 bytes from icmp_seq=3D2 ttl=3D255 time=3D33.481 ms


   I also checked the netmasks on the external interfaces for systems A
and B, and they match (they are assigned by the dhcp).

   As I stated earlier, A and B and physically next to each other, and
they share the same cable modem, the same dhcp, same isp, etc. I tried
disabling the firewall, but that didn't change anything.

   I know absolutely nothing about networking, but I feel like blaming
the isp for something. Anyone know what could be wrong? Any suggestions
what I should try?

Kind Regards,
Jan Danielsson
Te audire non possum. Musa sapientum fixa est in aure.

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