zone file question

[Mark_Andrews at isc.org]

> 
> I have a question about the generic zones listed in RFC1912. The RFC 
> explains that two zones, 0.in-addr.arpa and 255.in-addr.arpa, should 
> always be set up to prevent queries of the network and broadcast 
> addresses from 'escaping' into the internet and hitting a root name server.
> 
> My question is; if my network is a classless network, should the two 
> zones still be called as above or should they match the network and 
> broadcast addresses of my network?
> 
> So, if my IP address space is 192.168.20/27 with a network address of 
> 192.168.20.64 and a broadcast address of 192.168.20.95, should the two 
> zones be called 64.in-addr.arpa and 95.in-addr.arpa?

	No.  0.0.0.0 is still used by machines that don't know their
	address and 255.255.255.255 is a valid broadcast address on
	all networks.  The purpose of those zones is to catch reverse
	lookups on those addresses.  0.in-addr.arpa catches reverse
	lookups on 0.x.x.x and 255.in-addr.arpa catches reverse lookups
	on 255.x.x.x.  Note these are the first (not last) octets of
	the addresses.

	However you should have a zone for the address range you are
	using.  Since you don't have a full /24 you should look at
	RFC 2317 and choose a method along with your address provider.
	
	64.20.168.192.in-addra.arpa and 95.20.168.192.in-addra.arpa
	are the start and end of this address range in the in-addr.arpa
	space.
	
	Mark
> 
> Andrew
> 
--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at isc.org