Red Hat Bugzilla – Bug 57764
Telnet clent slow to connect unless full DNS name is used
Last modified: 2010-03-25 08:07:12 EDT
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User-Agent: Mozilla/4.78 [en] (Windows NT 5.0; U)
Description of problem:
I have just upgraded my RedHat Linux machine from version 6.2 to version
7.2 and I am having a problem with the telnet program. It seems that when
I try to telnet to another device it is taking anywhere from 30 to 60
second before I get the login prompt. This occurs only when I use the DNS
name for the device I am trying to telnet to and when I leave off the
domain part of the DNS name. An example would be "telnet xyz" I have the
problem, but not if I use "telnet xyz.mydomain.com". If I do a "ping xyz"
it works fine. I have check all my network setting and see no problem with
configuration. I have the domain and name servers defined, and I checked
the resolve.conf file and again see the name servers and domain defined in
the file. If I telnet from my windows 2000 workstation, which is on the
same local network as the Linux workstation, the telnet works just fine,
and I see no difference on the windows workstation in doing a "telnet xyz"
from a "telnet xyz.mydomain.com" in the time for the login prompt to come
back. It is basically instantaneous. It also instantaneous in receiving
the login prompt when doing a "telnet xyz.mydomAin.com" from the Linux
workstation. The problem again is when I leave off the domain part of the
address, in other words "telnet xyz" take anywhere from 30 to 60 seconds
to get back the login prompt. I did not have this problem while running
Redhat 6.2. This problem only appeared after upgrading to Redhat 7.2 . Any
suggestions to what is causing this problem.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1.telnet xyz instead of telnet xyz.mydomain.com
Actual Results: it takes around 60 seconds to connect.
Expected Results: Should have connected instantly
I ran a data capture on this problem and found that the telnet program is
not appending the local domain to the request, which is causing a rather
long DNS search for the name. When I telnet to xyz the telnet program
should be appending mydomain.com to the request, but the program is not
doing that. Istead it is sending the name xyz to the DNS server and I am
having to wait for the DNS failure before the program appends the
mydomain.com to the host name xyz.
well, that is default behaviour... isn't it??
first resolv xyz, then append every search string to xyz as defined in
/etc/resolv.conf and try to resolv that...
if you use xyz that often, just add it to /etc/hosts and give your
xyz.mydomain.com that xyz as an alias.
This was probably caused of getaddrinfo and PF_UNSPEC: