DNS troubleshooting

Some tips when troubleshooting DNS.

Windows tools: nslookup google.com
Linux tools: dig google.com

Check for double DNS servers, named and dnsmasq may conflict and then both want to occupy port 53.

netstat -l -n|grep 53

Set the following in /etc/dnsmasq.conf:

log-facility=/var/log/dnsmasq.log
log-queries

A working dnsmasq will pump out every request in this file, like this:
Mar 28 11:31:52 dnsmasq[2668]: cached safebrowsing-cache.google.com is <CNAME>
Mar 28 11:31:52 dnsmasq[2668]: cached safebrowsing.cache.l.google.com is 173.194.113.136
Mar 28 11:31:52 dnsmasq[2668]: cached safebrowsing.cache.l.google.com is 173.194.113.133

A non-working one is quiet.

Use Wireshark to capture dns packages, filter on only dns.





This is a personal note. Last updated: 2014-03-28 11:35:34.



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Don't forget to pay my friend a visit too. Joakim