Q: DNS query format

[Mark Andrews]

> 
> Is this DNS query correct?:
> 
> Domain Name System (query)
>     Transaction ID: 0x938a
>     Flags: 0x0110 (Standard query)
>         0... .... .... .... = Response: Message is a query
>         .000 0... .... .... = Opcode: Standard query (0)
>         .... ..0. .... .... = Truncated: Message is not truncated
>         .... ...1 .... .... = Recursion desired: Do query recursively
>         .... .... .0.. .... = Z: reserved (0)
>         .... .... ...1 .... = Non-authenticated data OK:
> Non-authenticated data
> is acceptable
>     Questions: 1
>     Answer RRs: 0
>     Authority RRs: 0
>     Additional RRs: 1
>     Queries
>        1.2.3.e164.arpa: type NAPTR, class IN
> 
> According to RFC1035, 3 reserved bits should be 0s. But  in my example
> second bit is 1 and even interpreted by Etherreal as "Non-authenticated
> data OK" flag.
> So is this a  legal  query? 
> 
> (the reason I'm asking is: this query is coming from  forward-only zone
> in bind9. We have custom ENUM server which doesn't accept this query.  )
> 
> TIA,
> Vitaly

	RFC1035 has been updated by a lot of other RFC's.  From
	the RFC Index at http://www.ietf.org/iesg/1rfc_index.txt.

	To fully understand the modern DNS you need to have read
	and understood all of these.

	Yes, it is legal.

	Mark

1033 Domain administrators operations guide. M. Lottor. November 1987.
     (Format: TXT=37263 bytes) (Status: UNKNOWN)

1034 Domain names - concepts and facilities. P.V. Mockapetris.
     November 1987. (Format: TXT=129180 bytes) (Obsoletes RFC0973,
     RFC0882, RFC0883) (Updated by RFC1101, RFC1183, RFC1348, RFC1876,
     RFC1982, RFC2065, RFC2181, RFC2308, RFC2535, RFC4033, RFC4034,
     RFC4035, RFC4343, RFC4035, RFC4592) (Also STD0013) (Status: STANDARD)

1035 Domain names - implementation and specification. P.V.
     Mockapetris. November 1987. (Format: TXT=125626 bytes) (Obsoletes
     RFC0973, RFC0882, RFC0883) (Updated by RFC1101, RFC1183, RFC1348,
     RFC1876, RFC1982, RFC1995, RFC1996, RFC2065, RFC2136, RFC2181,
     RFC2137, RFC2308, RFC2535, RFC2845, RFC3425, RFC3658, RFC4033,
     RFC4034, RFC4035, RFC4343, RFC2137, RFC2845, RFC3425, RFC3658,
     RFC4035, RFC4033) (Also STD0013) (Status: STANDARD)
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at isc.org