|dnstrace(1)||General Commands Manual||dnstrace(1)|
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.
In versions 1.03 and above: You can pipe dnstrace through dnstracesort(1) 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(1) to see the results so far:
dnstracesort < AOL | less
Beware that, as of January 2001, dnstrace produces more than 5 megabytes of output for the complete trace of cr.yp.to starting from all the root servers. It ends up sending more than 6000 queries to more than 200 different servers.