Re: router -i

[Matti Aarnio <mea@utu.fi>]

> I know I'm going to feel stupid when I read the answer to this, but
> perhaps someone here can explain to me what I'm doing wrong. This has to
> do with the router interactive testing. 

	Your ``mileage'' on feelings may vary...

> The following seems to be new in zmailer 2.99.26, but it may also have
> been the same with one or more earlier versions since it is a while since
> I refreshed all my .cf files and installed zmailer 'clean' with new
> everything. However, I *know* this used to work with previous 2.99.xx
> versions - I just can't say when it stopped working. 

	Actually never, it has always worked like this.

> Now (at last), the problem. I use router -i to interrogate the router as
> follows: 
> 
>  server:/# /usr/libexec/mail/router -i
>  ZMailer router (2.99.26 #1: Mon Feb 12 22:30:09 EST 1996)
>    davidn@server:/usr/src/zmailer-2.99.26/router
>  Copyright 1992 Rayan S. Zachariassen
>  Copyright 1992-1996 Matti Aarnio
> 
>  z# router davidn@sdev.blaze.net.au
>  <davidn.interactive@blaze.net.au>: address: davidn@sdev.blaze.net.au
>  (((smtp sdev.blaze.net.au davidn@sdev.blaze.net.au default_attributes)))
>  z#
> 
> This tels me that it'll attempt to deliver an item of email via smtp to
> sdev.blaze.net.au when sent to that address, right? 

	Right.

> However, the MX record for sdev.blaze.net.au
> 
>  SU server:/# nslookup
>  Default Server:  server.blaze.net.au
>  Address:  203.17.53.1
> 
>  > set type=MX
>  > sdev.blaze.net.au
>  Server:  server.blaze.net.au
>  Address:  203.17.53.1
> 
>  sdev.blaze.net.au  preference = 10, mail exchanger = unique.blaze.net.au
>  sdev.blaze.net.au  preference = 20, mail exchanger = server.blaze.net.au
>  sdev.blaze.net.au  preference = 100, mail exchanger = yarrina.connect.com.au
>  ~
> 
> As you can see, the preferred MX target is unique.blaze.net.au. Why
> doesn't router -i show this? 

	Because it will just check for canonic name of the host,
	and if it is incomplete (within your local domain), or
	a CNAME, rewrite that.  Then it will check, if the target
	address has A or MX (if not, error report/hold channel),
	however it won't list those possible MXes.

	Actual USE of MXes is far latter when the SMTP-TA is making
	connection to the remote machine, and for it the router
	must give the original target information -- othervice it
	could try to pick wrong server..   Consider:

	target-A	IN MX 1 server-B
			IN MX 2 server-C
			IN MX 3 server-D
	server-B	IN MX 1 server-C
			IN MX 2 server-D

	Now if the router gives out instead of  target-A  direct to
	server-B, we are in violation of MX rules on message routeing.
	(MXed server is not eligible for MX lookup in place of the
	 original target system.)

> BTW, delivery works perfectly. Mail actually addressed to
> *@sdev.blaze.net.au is actually sent to unique.blaze.net.au. It's just a
> little annoying that it doesn't indicate this when run in interactive
> mode. Looking at the output of a mail -v send to sdev.. it appears that MX
> lookup is now delayed until the scheduler (streamlining?)? I guess that's
> ok - assuming this is the way it was designed - but is there any way of
> having "router -i" do this for the purposes of testing? 

	To report the MXes ?
	Perhaps by:
		trace bind


	The MX-reports you see with  "mail -v" come from  smtp program.

> Regards,
> David

	/Matti Aarnio <mea@utu.fi>