Does BIND9 support broadcast/multicast query?

[Hideshi Enokihara]

On Wed, 28 Dec 2005 09:17:59 +1100
Mark Andrews <Mark_Andrews at isc.org> wrote:

> 
> > Hideshi Enokihara wrote:
> > > Thank you for your reply.
> > > 
> > > On Mon, 26 Dec 2005 09:58:54 -0800 (PST)
> > > Gregory Hicks <ghicks at cadence.com> wrote:
> > > 
> > > 
> > >>>Date: Mon, 26 Dec 2005 19:30:23 +0900
> > >>>From: Hideshi Enokihara <Hideshi.Enokihara at jp.yokogawa.com>
> > >>>To: bind-users at isc.org
> > >>>Subject: Does BIND9  support broadcast/multicast query?
> > >>>
> > >>>Hi all,
> > >>>
> > >>>I have a simple question for BIND9.
> > >>>
> > >>>Does BIND9 support a UDP query that is delivered using an IP
> > >>>broadcast or multicast address?
> > >>
> > >>broadcast/multicast is handled by the router long before the request
> > >>ever reaches the server.  As far as the SERVER is concerned, it just
> > >>sees a request and processes normally.
> > > 
> > > 
> > > I see.
> > > But RFC1123 says,
> > > 
> > >             A server MAY support a UDP query that is delivered using an
> > >             IP broadcast or multicast address.  However, the Recursion s
> > >             Desired bit MUST NOT be set in a query that is multicast,
> > >             and MUST be ignored by name servers receiving queries via a
> > >             broadcast or multicast address. 
> > > 
> > > So, I think that sarver may support a broadcast or multicast query, Not rou
> > ter.
> > > How do you think?
> > > 
> > The only part of RFC 1123 that is relevant to this question as far as I
> > could see was Section 6.1.3.2 where the discussion at the end of the
> > section discourages broadcast and multicast for finding name servers.
> > I don't remember seeing RFC's suggesting that nameservers support
> > broadcast or multicast for anything.
> > 
> > Danny
> 
> 
> 	BIND 9 does not support multicast queries.  It does not
> 	have code to join a multicast group so it will never recieve
> 	multicast queries.
> 
> 	As for broadcast queries it will respond to them however there
> 	is no code in the resolver to special case that the source
> 	address of the reply won't match the address the query was
> 	sent to.

I tried to test for broadcast query.
But, BIND9 did not send response for the broadcast query. 

I built the following networks.

Net-z   --+--------------------------+-------- 
          |                          |          192.168.0/24
          |example.com domain        |
        DNS Server1 (BIND9)            DNS Cient1
           192.168.0.10                192.168.0.20


example.com zone file is following
(This file was set to BIND9)

$TTL    86400           ; TTL of 1 day
@ IN SOA NS1.example.com. root.example.com. (
	2005081600	; serial
	3600		; refresh every 1 hr
	900		; retry every 15 min
	604800		; expire after a week
	3600		; Minimum TTL of a 1 hr
)
;
	IN	NS	NS1.example.com.
NS1	IN	A	192.168.0.10
;
A	IN	A	192.168.1.10

And send query for broadcast to BIND9.
Tcpdump result is following.

--------------------------------
NS1# tcpdump -i bfe0 -s 2046 
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on bfe0, link-type EN10MB (Ethernet), capture size 2046 bytes
11:24:11.496830 IP 192.168.0.20.callbook > 192.168.0.255.domain:  4096 A? A.example.com. (31)
--------------------------

Best Regards,

> 	Mark
> --
> Mark Andrews, ISC
> 1 Seymour St., Dundas Valley, NSW 2117, Australia
> PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at isc.org


-- 
*************************************
Hideshi Enokihara
IPv6 Business
Network & Software Development Dept.
Yokogawa Electric Corporation