adding additional CNAME records for redundancy
adding additional CNAME records for redundancy
Hello everyone! I'm trying to grasp this CNAME RR configuration question. On the registrar, I see that when I create a CNAME record like CNAME host: www.test.com points to test.com, it works as expected—browsers go to test.com. But I'm confused about the mail server settings for test.com. Some admins add entries such as CNAME host: mail.test.com pointing to test.com and CNAME host: www.mail.test.com also pointing to test.com. How do these work? Why are they added? Can you clarify how they should be entered? Thanks!
It doesn’t seem helpful to me. I don’t usually do that either—there’s no real benefit. I typically send mail directly to the mail server and add an autodiscover record (since I mostly use Microsoft Exchange). The CNAMEs you’re using are mainly for catching users who enter the wrong URL.
This indicates a typical DNS scenario. If an A-record for domain test.com points to the same IP as mail.test.com and www.mail.test.com, you can redirect those aliases (CNAMEs) to that single address. Updating the IP only requires changing one entry instead of three.
These features are mainly for simplicity. I don’t use CNAMES because they require a double lookup compared to A records, but for businesses with many subdomains it could save time when switching hosts. I think the main purpose of mail. is still ease of use for companies. That way, if traffic spikes and you move your mail server, you won’t have to ask everyone to update their domain names in clients. From an efficiency standpoint, you’d never rely on CNAMEs.
It seems it was more crucial when things were simpler and DNS queries were expensive due to poor ISP DNS services before major providers like Google and Cloudflare existed.