Q: DNS query format

[Vitaly Karasik]

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