DNS record, A record, MX record definitions
1) What is a DNS & How does it work with TCP/IP?
2)What is A record & How does it work?
3)What MX record & How does it work?
4)How to configure A record & MX record in IIS?
While these aren't really Domino specific, they are integral questions for mail routing. DNS is Domain Name Service, and it is a part of most operating systems. Global DNS refers to the DNS records of public records, such as https://searchdomino.techtarget.com/. When you type in the URL, it has to refer to something, which would be the IP address. Since it is much easier to remember www.searchdomino.com than it is 1.2.3.4, we use DNS for name resolution.
An A record, simply, is a pointer or alias record. It is very much like a DNS entry, but you can use it to point one IP address to another, for forwarding purposes.
A MX record is the Mail Exchanger record. This tells the world what your mail server IP address and name is so that you can receive SMTP e-mail.
DNS is setup (globally) usually through your ISP or through your domain registrar. The same goes for your global MX records. Internally, you can setup your own DNS via Windows. Consult any Windows NT/2000 manual for this.