Chaining CNAMEs?

[Kevin Darcy]

Chris De Young wrote:
> Hi,
> I was just browsing through the latest edition of the O'Reilly
> DNS/BIND book, and ran across a bit on pointing a CNAME record at
> another alias:
>
> "The answer is yes: you can chain together CNAME records. The BIND
> implementation supports it, and the RFCs don't expressly forbid it."
>
> The authors go on to recommend against it anyway, but I had always
> thought that this was actually illegal.  I don't remember now where I
> had gotten that idea... I think the issue had to do with not being
> guaranteed that the server would always do the additional processing
> to ensure that you got to the canonical name at the end of the chain.
>
> I guess I've been mistaken?  :-)
>
>   
RFC 1034, Section 3.6.2

[...]

Domain names in RRs which point at another name should always point at
the primary name and not the alias.  This avoids extra indirections in
accessing information.

---

I've never understood why BIND is so liberal about this, when it's so strict about some many other things. Surely it can't be because of the "should" language, can it? Given the time and context in which 1034 was written, that "should" is to be treated as a MUST for all practical intents and purposes.

							- Kevin