Date: Thu, 02 Jan 1997 19:55:45 +0100 From: sthaug@nethelp.no To: wpaul@skynet.ctr.columbia.edu Cc: freebsd-current@FreeBSD.ORG Subject: Re: Resolver Error 0 (no error) Message-ID: <16606.852231345@verdi.nethelp.no> In-Reply-To: Your message of "Thu, 2 Jan 1997 11:26:50 -0500 (EST)" References: <199701021626.LAA10553@skynet.ctr.columbia.edu>
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> [/homes/wpaul]:marple{15}% traceroute freebsd.org
...
> 4 nyser-gw.net.columbia.edu (128.59.247.1) 189.497 ms 112.663 ms 100.243 ms
> 5 169.130.12.5 (169.130.12.5) 91.750 ms 98.124 ms 102.126 ms
> 6 169.130.1.101 (169.130.1.101) 82.285 ms 74.644 ms 79.732 ms
> 7 144.228.60.1 (144.228.60.1) 281.282 ms 141.881 ms 219.776 ms
> 8 198.67.2.11 (198.67.2.11) 118.587 ms 110.496 ms 113.735 ms
> 9 144.228.10.102 (144.228.10.102) 259.932 ms 149.262 ms 149.992 ms
> 10 144.228.10.50 (144.228.10.50) 231.764 ms 217.007 ms 238.777 ms
> 11 pb-nap.crl.net (198.32.128.20) 147.369 ms 156.685 ms 149.741 ms
...
> FreeBSD 2.2-BETA_A
>
> Hops 5 through 10 didn't reverse resolve correctly, but:
>
> [/homes/wpaul]:marple{17}% nslookup 169.130.12.5
> Server: sirius.ctr.columbia.edu
> Address: 128.59.64.60
>
> Name: ny-nyc-2-H4/0-T3.nysernet.net
> Address: 169.130.12.5
> Granted this is Sprint we're talking about here, but this seems a little
> odd. My named is from BIND 4.9.5-REL.
This is not related to your named but to the resolver version used by
the gethostbyaddr() function in traceroute. The behavior changed from
bind-4.9.3 to bind-4.9.4: Characters which are supposed to be illegal
(/ and _ among others) result in gethostbyaddr() returning a NULL
pointer.
All the routers in hops 5 through 10 have / in the names, thus a
traceroute which uses a 4.9.4 (or newer) resolver will not translate
the IP address back to a name.
If you want to see an even more curious demonstration of the same, you
can try the 'host' program from 4.9.3 (or older) versus 'host' from
4.9.4 or newer:
% host-493rel 169.130.12.5
Name: ny-nyc-2-H4/0-T3.nysernet.net
Address: 169.130.12.5
% host-494p1 169.130.12.5
Host not found, try again.
but:
% host-494p1 -t ptr 5.12.130.169.in-addr.arpa
5.12.130.169.in-addr.arpa PTR ny-nyc-2-H4/0-T3.nysernet.net
(For the curious: 'host -t ptr ...' does *not* use the gethostbyaddr()
function from the resolver library, while 'host <IP addr>' does.)
Steinar Haug, Nethelp consulting, sthaug@nethelp.no
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