It's inefficient to specify a large number of hosts in the facebook.com domain instead of blocking the whole domain.

For this, you can run dnsmasq and use the "--address" option or "address" command in dnsmasq.conf:

  $ man dnsmasq
  [...]
       -A, --address=/<domain>/[domain/]<ipaddr>
              Specify an IP address to  return  for  any  host  in  the  given
              domains.   Queries in the domains are never forwarded and always
              replied to with the specified IP address which may  be  IPv4  or
              IPv6.  To  give  both  IPv4 and IPv6 addresses for a domain, use
              repeated -A flags.  Note that /etc/hosts and DHCP  leases  over‐
              ride this for individual names. A common use of this is to redi‐
              rect the entire doubleclick.net domain to  some  friendly  local
              web  server  to avoid banner ads. The domain specification works
              in the same was as for --server, with  the  additional  facility
              that  /#/  matches  any  domain.  Thus --address=/#/1.2.3.4 will
              always return 1.2.3.4 for any query not answered from /etc/hosts
              or  DHCP  and  not sent to an upstream nameserver by a more spe‐
              cific --server directive.