dnstrace - DNS lookup tool
dnstrace t fqdn r
dnstrace searches for all DNS servers that can affect the resolution of
records of type t under the domain name fqdn, starting from the root
server r. You can list more than one root server.
dnstrace uses the standard DNS resolution algorithm, but follows all
possible paths in the algorithm. It prints all responses it receives
from DNS servers; it also prints warnings about slow servers, dead
servers, misdelegated (``lame'') servers, and misformatted packets.
dnstrace is similar in spirit to DOC and dnswalk but is much more
effective than those tools at debugging resolution problems.
You can pipe dnstrace through dnstracesort for human-friendly output.
dnstrace can take a long time to run, so standard procedure is to save
its output in a file:
dnstrace any www.aol.com a.root-servers.net > AOL &
Then you can run dnstracesort to see the results so far:
dnstracesort < AOL | less
The dnstracesort output uses ul codes for boldface and underline; these
codes are displayed properly by less.
Beware that, as of February 2000, dnstrace produces half a megabyte of
output for the complete trace of a typical .com name starting from all
the root servers. There are more than 200 computers around the world
that can affect all .com names. Including IPv6 address lookup (June
2018) the amount of output data is roughly doubled.
dnsip(1), dnsipq(1), dnsmx(1), dnstxt(1), dnsqr(1), dnsq(1),
Man(1) output converted with