DNS/Troubleshooting

Testing Resources

Configuration Tests

• http://dnscheck.pingdom.com/
• https://mxtoolbox.com/DNSCheck.aspx
• https://isc.sans.edu/dnstest.html

DNSSEC Tests

• http://dnssec-debugger.verisignlabs.com
• http://dnsviz.net
• http://viewdns.info/dnssec/

DNS Global Speed Tests

• https://www.whatsmydns.net
• https://dnschecker.org/

Testing a DNS Entry with dig

First git the list of DNS root servers by using the following command

dig ns . +short

You should get a list of the different root servers that will look like this (but in a different order).

e.root-servers.net.
d.root-servers.net.
b.root-servers.net.
l.root-servers.net.
k.root-servers.net.
m.root-servers.net.
i.root-servers.net.
g.root-servers.net.
j.root-servers.net.
a.root-servers.net.
c.root-servers.net.
f.root-servers.net.
h.root-servers.net.

Choose one at random, and run the below dig query to find the list of NS servers for the TLD (Top Level Domain) you are looking up for (for example .us .edu .com)

Or if you are checking the domain umn.edu, your full list of commands would be:

dig ns .  # Get list of Root Servers
dig ns edu. @l.root-servers.net.  # Get list of Name Servers for TLD edu
dig ns umn.edu. @g.edu-servers.net.  # Get list of Name Servers for domain umn.edu
dig a www.umn.edu. @ns-auth-1.umn.edu.  # get the A record for host www.umn.edu