>Number:         10724
>Category:       bin
>Synopsis:       arp does not show hostname when DNS not available
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Jul 31 09:02:01 PDT 2000
>Closed-Date:
>Last-Modified:
>Originator:     Martin Husemann
>Release:        1.5C, cvs updated July 28
>Organization:
	
>Environment:
	
System: NetBSD rumolt.teuto.de 1.5C NetBSD 1.5C (RUMOLT) #2: Mon Jul 31 10:09:57 MEST 2000 martin@rumolt.teuto.de:/usr/src/sys-i4b/arch/i386/compile/RUMOLT i386


>Description:

I have a dial-up connection to my ISP and am using his nameserver. I'm not 
using a local (caching only) named, because that wouldn't normaly buy me
anything.

/etc/resolv.conf is set to file dns for the hosts lookup.

Whith the dial-up connection disabled (i.e. offline) I get the following:

[/etc] martin@rumolt > ping -c 2 hwart; arp -a
PING hwart.teuto.de (212.8.203.83): 56 data bytes
64 bytes from 212.8.203.83: icmp_seq=0 ttl=128 time=0.476 ms
64 bytes from 212.8.203.83: icmp_seq=1 ttl=128 time=6.674 ms

----hwart.teuto.de PING Statistics----
2 packets transmitted, 2 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 0.476/3.575/6.674/4.383 ms
reginas.teuto.de (192.168.247.1) at 00:00:8f:48:28:d2 permanent
? (192.168.247.255) at (incomplete)
? (212.8.203.81) at 00:80:c8:f9:e4:37 permanent
? (212.8.203.83) at 00:a0:c9:25:13:84
? (212.8.203.87) at (incomplete)

Note that it is possible to use the name in the ping command, but arp is
not able to do reverse lookup.

Now with the dial-up connection enabled I get:

[/etc] martin@rumolt > ping -c 2 hwart ; arp -a
PING hwart.teuto.de (212.8.203.83): 56 data bytes
64 bytes from 212.8.203.83: icmp_seq=0 ttl=128 time=0.310 ms
64 bytes from 212.8.203.83: icmp_seq=1 ttl=128 time=6.064 ms

----hwart.teuto.de PING Statistics----
2 packets transmitted, 2 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 0.310/3.187/6.064/4.069 ms
reginas.teuto.de (192.168.247.1) at 00:00:8f:48:28:d2 permanent
? (192.168.247.255) at (incomplete)
rumolt.teuto.de (212.8.203.81) at 00:80:c8:f9:e4:37 permanent
hwart.teuto.de (212.8.203.83) at 00:a0:c9:25:13:84
local-net-bc.teuto.de (212.8.203.87) at (incomplete)

Further note: the local-net-bc.teuto.de lookup of my local broadcast
address comes from /etc/hosts, it's not listed on the nameserver. The
same is true for the first line in the first case: the host on the NAT
subnet with permanent entry does not have any dns entry - but still is listed
in the first example.

Apparently arp tries to do the lookups in sequential order and as soon as
the first try fails it shows ? for all following entries. I don't know why
it fails for some and doesn't for others.

>How-To-Repeat:
s.a.
>Fix:
n/a
>Release-Note:
>Audit-Trail:
>Unformatted: