In article <gllr91$2vq...@sf1.isc.org>, Scott Haneda <talkli...@newgeo.com> wrote:
> I have never got why this is such a hard thing for email admins to get > right, but it certainly causes me headaches. I personally wish > CNAME's would just go away, keep them around, but just stop talking > about them, then new to DNS users would not use them. Suppose you're providing an MX service, but you actually out-source the operation to a third party. You want to give your customers an MX record that points to a name in your domain, so they don't need to know about the third party (and so you have the flexibility to change your out-sourcing without requiring all customers to update their MX record). But the third party also needs the flexibility to change the IP of the server, load balancing, disaster recovery, changing ISPs, etc. So they don't want you to hard-code their IPs into your domain. CNAMEs are the simplest solution to implementing all this. customer.com. IN MX 10 mx.yourdomain.com. mx.yourdomain.com. IN CNAME mx.outsourcer.com. mx.outsourcer.com. IN A ... If the customer changes MX services, they change their MX record. If you change outsourcing companies, you change your CNAME record. And if the outsourcing company re-IPs their server, they change the A record. Everyone can perform their job without having to make any of the downstream customers adjust their records. -- Barry Margolin, bar...@alum.mit.edu Arlington, MA *** PLEASE don't copy me on replies, I'll read them in the group *** _______________________________________________ bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
