name resolution puzzle
Valeri Galtsev
galtsev at kicp.uchicago.edu
Fri Aug 3 21:41:50 UTC 2018
Dear Experts,
I just noticed some behavior of commands "host" and "nslookup" that
puzzles me. Namely, they do not query /etc/hosts file first, but query
nameserver instead, even though nsswitch.conf order is "files dns":
$cat /etc/nsswitch.conf | grep hosts
hosts: files dns
$ cat /etc/hosts | grep holometer.uchicago.edu
128.135.20.84 holometer holometer.uchicago.edu
$ host holometer.uchicago.edu
holometer.uchicago.edu has address 128.135.52.70
$ nslookup holometer.uchicago.edu
Server: 128.135.249.50
Address: 128.135.249.50#53
Name: holometer.uchicago.edu
Address: 128.135.52.70
So, it appears, that the commands "host" and "nslookup" go directly to
DNS server, and do not look into /etc/hosts first which I have expected.
I should mention that other compiled programs do obey the nsswitch.conf
query order.
Can someone enlighten me on this?
The reason I have different IP in /etc/hosts is: I'm building the box to
migrate some host to, and I'd like to test some stuff that should work
from other machines before I switch DNS records to new IP. So, on these
external machines I am trying to have hostname resolve into future IP
just by adding it to /etc/hosts.
Thanks.
Valeri
--
++++++++++++++++++++++++++++++++++++++++
Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247
++++++++++++++++++++++++++++++++++++++++
More information about the freebsd-questions
mailing list