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In article <21448@cornell.UUCP> parmelee@wayback.cs.cornell.edu (Larry Parmelee) writes:

Commenting on an earlier article of mine about sendmail's name canoncialization:

>Chet, In article <99@cwjcc.CWRU.Edu> you write:
>> 2.  In ruleset 0 of your sendmail.cf, add a rule like this that asks the
>>     resolver if a host is in the name server:
>> 
>> 	R$+<@$+>$*		$:$1<@[$ $2. $]>$3
>> 
>>     This tells sendmail to canonicalize the host name it's currently focusing
>>     on, with a dot appended. If the host is found, the host name is rewritten
>>     and will lose the dot at the end.

>You need to be careful about the above method.  In the 4.8 version
>of BIND (sendmail 5.59), a trailing dot is taken to indicate a
>rooted name.  For example, if I lookup "devvax.tn" here, it
>changes into "devvax.tn.cornell.edu", but if I lookup "devvax.tn.",
>it fails, because the trailing dot tells the resolver routines that
>the name is to be looked up as if "tn" existed at the same level as
>"edu", "com", or "gov".

That's true, and is probably applicable for some situations that exist out 
there.  However, here are a couple of comments about our situation, which is
(obviously) what our sendmail.cf is tailored for:

1.  You seem to be using a default domain for non-rooted lookups.  We, for 
    various reasons, do not.  What we do do is ensure that each host
    in the CWRU.EDU domain has a globally unique name within that domain,
    and put in CNAME records as aliases for each of those names 
    (e.g. CNAME cwjcc -> cwjcc.CWRU.EDU, CNAME alpha -> alpha.ces.cwru.edu,
    and so on).  This way our users (most of whom are pretty unsophisticated)
    can get the benefits of just having to remember user@host for on-campus   
    mail, even if the host is a member of a subdomain.  I think this is 
    basically what you are doing, you're just going about it a different way.
    My feeling is that what we are doing is The Right Way To Go, at least
    for this campus.

2.  I don't think there's an easier way to do name canonicalization at the
    sendmail.cf (mailer, host, user) resolution level, and it's very 
    important that we send as much mail as we can out via our Internet 
    connection.

I also don't think that people should treat subdomains as part of the host
name, which is, in essence, what you are doing above.  Of course, that's
probably just personal preference (it's all or nothing).

Chet Ramey
chet@cwjcc.CWRU.EDU


| Chet Ramey            chet@cwjcc.CWRU.EDU    chet@alpha.CES.CWRU.EDU
|
|		Just another jerk takin' pride in his work...