NAME

       dnstcpbench - tool to perform TCP benchmarking of nameservers

SYNOPSIS

       dnstcpbench [OPTION]... REMOTE-ADDRESS [REMOTE-PORT]

DESCRIPTION

       dnstcpbench reads DNS queries (by default from standard input) and sends them out in parallel to a remote
       nameserver.  By  default  TCP/IP  is  used,  but  optionally,  UDP  is  tried first, which allows for the
       benchmarking of TCP/IP fallback.

       The program reports both mean and median numbers for queries per second and UDP  and  TCP  latency.  Each
       query  only counts once, even if it is tried over UDP first. This effectively means that passing '-u' can
       lower query rates if many queries get shunted to TCP.

       The input format is one query per line: qname single-space qtype. An example:

          www.powerdns.com ANY

       When benchmarking extended runs, it may be necessary to enable TIME_WAIT recycling, as TCP/IP port tuples
       may otherwise run out. On Linux this is performed by running:

          echo 1 > /proc/sys/net/ipv4/tcp_tw_recycle

       The equivalent for IPv6 is not known.

OPTIONS

       -f, <FILENAME>, --file <FILENAME>       FILENAME from which to read queries. Defaults to  standard  input
       if  unspecified.   -h,  --help                               Provide  a  helpful message.  --timeout-msec
       <MSEC>                     MSEC   milliseconds   to   wait    for    an    answer.     -u,    --udp-first
       Attempt  resolution  via  UDP  first,  only  do  TCP  if  truncated  answer  is  received.  -v, --verbose
       Be wordy on what the program is doing.  --workers <NUM>                         Use NUM  parallel  worker
       threads.

       REMOTE-ADDRESS: IPv4 or IPv6 to test against.

       REMOTE-PORT: Port to test against, defaults to 53.

BUGS

       Currently  the  timeout code does not actually perform non-blocking connects or writes. So a slow connect
       or slow writes will still cause low performance and delays.

       Median queries per second statistics are reported as 0 for sub-second runs.

AUTHOR

       PowerDNS.COM BV

COPYRIGHT

       PowerDNS.COM BV

                                                  Jul 07, 2025                                    DNSTCPBENCH(1)