The s6-dnsq program

s6-dnsq is an analysis and debug tool. It performs a non-recursive DNS query to a given list of servers, then prints the contents of the answer packet, and optionally debug information during the resolution.

Interface

     s6-dnsq [ -1 | -2 ] [ -t timeout ] [ -D level ] qtype domain serverlist

s6-dnsq makes an iterative DNS query of type qtype for the name domain to serverlist. It prints the answer packet, in human-readable form, to its standard output, then exits 0.
It does not qualify domain.
If the resolution fails for some reason, s6-dnsq exits 2.
serverlist is a list of IP addresses (v4 or v6), one or more addresses per argument on the command line (so you can use, for instance, `s6-dnsip4 ns.example.com` as argument, and get all the addresses for ns.example.com in your server list). Servers are tried in the order given, until a definitive answer is obtained or s6-dnsq runs out of server addresses.

Options

-1 : send debug information to stdout.
-2 : send debug information to stderr. This is the default. Note that those options only apply to debug output, not to the regular packet dump, which is always printed to stdout.
-t timeout : if the resolution takes more than timeout milliseconds, then it exits 99 right away with an error message. By default, timeout is 0, which means no timeout.
-D level : produce debug output during resolution. If level is:
- 0: no debug output is produced
- 1: information is printed when s6-dnsq receives a DNS packet from a server
- 2: information is printed before and after s6-dnsq sends a DNS packet to a server
- 3: both 1. and 2. apply

Notes

TXT records are printed in a quoted form similar to s6-quote's output.
If s6-dnsq finds a record it cannot print, such as an unknown RR type, it dumps its contents in the same quoted form.
The normal output format should be stable, so you can write programs that automatically parse it. However, the debug output format is undocumented and subject to change.