Well Known Service resource.
The host these services run on.
A bit map of enabled services on this host.
If protocol is 6 (TCP) then the 26th bit corresponds to the SMTP service (port 25). If this bit is set, then an SMTP server should be listening on TCP port 25; if zero, SMTP service is not supported.
IP protocol number for these services.
# File lib/resolv.rb, line 2198 def initialize(address, protocol, bitmap) @address = IPv4.create(address) @protocol = protocol @bitmap = bitmap end