Usage:
  clockdiff [options] <destination>

Options:
                without -o, use icmp timestamp only (see RFC0792, page 16)
  -o            use IP timestamp and icmp echo
  -o1           use three-term IP timestamp and icmp echo
  -T, --time-format <ctime|iso>
                  specify display time format, ctime is the default
  -I            alias of --time-format=iso
  -h, --help    display this help
  -V, --version print version and exit
  <destination> DNS name or IP address

For more details see clockdiff(8).