[lug] Connection problems

[Matt Clauson]

On Wednesday 21 November 2001 12:10, Chris Wade hastily scribbled the 
following:
> > Have you done DNS sanity checks on the remote machine (ie: it can
> > resolve the IP you're connecting from, the DNS servers aren't down,
> > etc.) -- otherwise it'll hang until the DNS lookup fails or times
> > out.
> Could you tell me how to do this?
>
> Is there a log on the remote machine that I could check?

on the remote machine, run a dig query:

$ dig -x <ip address of remote machine>

It should come back with the PTR record pointing to the host name, or 
with an NXDOMAIN response.  In no case, I believe, should it come back 
with a SERVFAIL response.

For an example, here's the result of a dig on one of my remote 
machines, for the IP address of my current dialup:

mec at webdragon:/export/home/mec$ dig -x 216.87.70.234

; <<>> DiG 8.3 <<>> -x
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 5, ADDITIONAL: 5
;; QUERY SECTION:
;;      234.70.87.216.in-addr.arpa, type = ANY, class = IN

;; ANSWER SECTION:
234.70.87.216.in-addr.arpa.  29m6s IN PTR  dyn2-234.mm.den.viawest.net.

;; AUTHORITY SECTION:
70.87.216.in-addr.arpa.  4d18h40m4s IN NS  stix.viawest.net.
70.87.216.in-addr.arpa.  4d18h40m4s IN NS  stones.viawest.net.
70.87.216.in-addr.arpa.  4d18h40m4s IN NS  ns1.viawest.net.
70.87.216.in-addr.arpa.  4d18h40m4s IN NS  ns2.viawest.net.
70.87.216.in-addr.arpa.  4d18h40m4s IN NS  ns3.viawest.net.

;; ADDITIONAL SECTION:
stix.viawest.net.       3h25m33s IN A   216.87.64.2
stones.viawest.net.     3h25m33s IN A   166.90.152.35
ns1.viawest.net.        3h25m33s IN A   216.87.64.12
ns2.viawest.net.        3h25m33s IN A   209.170.216.2
ns3.viawest.net.        29m6s IN A      166.90.152.37

;; Total query time: 2 msec
;; FROM: webdragon to SERVER: default -- 127.0.0.1
;; WHEN: Wed Nov 21 12:29:03 2001
;; MSG SIZE  sent: 44  rcvd: 259

HTH.  YMMV, of course.

--mec