Name based hosts and bind

[Barry Margolin]

In article <fup0ab$jpu$1 at sf1.isc.org>,
 "Bob Hoffman" <bob at bobhoffman.com> wrote:

> Okay, I will try to be more diligent.
> 
> I have a theoretical website that is ipbased. I add another theoretical
> website that uses the same ip number, this is what is called 'name based'.
> 
> Two websites, the ip-based www.mysite.com and the name based
> www.mysitename.com. They both use the same ip address and in the named.conf
> a master is made for each and a zone file is added to the var/named folder. 
> 
> However, an addr.arpa cannot be made for each since they use the same exact
> ip address.
> 
> Therefore, the addr.arps file for this ip address will return only one PTR
> record. 
> 	IN	PTR	mysite.com
> 
> And not mention the other one, mysitename.com

No problem.  Web sites don't care about PTR records.  Name based virtual 
hosts use the HTTP Host: request-header to determine which one is being 
accessed.

> 
> The mention of mx records was perhaps a general term, let me rephrase. Each
> of these theoretical websites HAS an MX record because they each have their
> OWN mail server. And since mail is sent out from mail.mysitename.com to a
> stringent aol, and aol looks up to find my PTR for mysitename.com to match
> my ip, they get nysite.com and bounce the mail back.

Assuming you're correct that AOL requires that the HELO name match the 
PTR record (I'm not sure this is true, because I think there are many 
legitimate mail servers that don't do this), both mail servers should 
send "HELO mysite.com", regardless of the web site's name, to make them 
happy.  Most other mail servers don't care.

> In other words, although there is a PTR record dealing with the correct ip,
> only the domain mysite.com is listed in it, not mysitename.com
> 
> Now name based sites are used as a term in virtual hosting, but do have the
> added problem of not having an ip to specifically make a addr.arpa file for
> that one domain, since there are multiple domains.
> 
> If you mean, it does not matter what the site listed in the PTR record is,
> and that the ip will resolve correctly anyway to either site (listed or not
> in the PTR) that is cool. But it seems kinda weird to just ignore the second
> site using the IP in the addr.arpa record.
> 
> To further define. Each site in its own zone file will have a IN A
> mail.thesite and a MX for mail.thesite. They will not be sharing the same
> 'mail.mysite.com' but instead have one of their own.

-- 
Barry Margolin, barmar at alum.mit.edu
Arlington, MA
*** PLEASE don't copy me on replies, I'll read them in the group ***