Subject: RFC 2782: "The SRV RR is unique"

From: Stuart Cheshire <[email-masked]>
Date: Fri, 15 Jun 2001 18:23:01 -0700

>     _Service._Proto.Name TTL Class SRV Priority Weight Port Target
>   Name
>     The domain this RR refers to.  The SRV RR is unique in that the
>     name one searches for is not this name; the example near the end
>     shows this clearly.

I understand that this text is intended to be helpful, but I feel it 
risks confusing the reader more than it helps.

As far as a name server implementation is concerned, an SRV record is 
simply a record type attached to a domain name (the word domain is used 
here in the strict RFC 1034 sense). The fact that this RFC recommends a 
certain naming convention, that the domain name to which the SRV record 
is attached should take the form "_Service._Proto.parentdomain.TLD", is 
of no special concern to a name server implementer.

To a name server implementer a query for an SRV record is merely a query 
specifying a given domain name, and record type "SRV". Any special naming 
conventions for that domain name are a contract between the client making 
the request, and the entity that placed the SRV record into the server. 
The server software itself need not know any of that; it need just obey 
normal DNS protocol rules. Indeed, neither BIND nor "nslookup" take any 
steps to reject SRV names that fail to follow this naming convention, as 
well they should not.

I suggest the following text:

>     _Service._Proto.Domain TTL Class SRV Priority Weight Port Target

>   Domain
>     The domain this RR refers to.  The SRV RR is unique in that the
>     names of all the SRV RRs for a domain appear logically as
>     children (subdomains) of that domain, with names constructed
>     programmatically according to the following convention:
>     SrvDomainName = _Service._Proto.ParentDomainName
>     The example near the end shows this clearly.

Stuart Cheshire <[email-masked]>
 * Wizard Without Portfolio, Apple Computer
 * Chairman, IETF ZEROCONF
 * www.stuartcheshire.org

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---

From: "Richard Barr Hibbs" <[email-masked]>
Date: Mon, 18 Jun 2001 12:00:25 -0700

The DHC working group "suggested" a way to construct the Client Identifier,
used to uniquely identify a client host to the server, and that has been
misused, abused, misinterpreted, misunderstood, and the source of many
rounds of discussion (argument??) about how to identify DHCP clients ever
since, with many users and some implementers believing that the text
required or demanded certain form and functionality that was not clearly
specified.

The lesson from the DHC working group is to be *very* careful about
"suggestions" for the content of items (in this case, the domain name for an
SRV record) because suggestions are often poorly implemented.

--Barr Hibbs

> -----Original Message-----
> From: Stuart Cheshire
> Sent: Friday, June 15, 2001 18:23
>