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What is the difference between an A record for a domain with a short TTL and a www CNAME with a short TTL? In other words, doesn't a short TTL get you essentia
by jwr 15y ago
What is the difference between an A record for a domain with a short TTL and a www CNAME with a short TTL?
In other words, doesn't a short TTL get you essentially the same thing?
- mjs 15y agoGood question. Is there an AWS limitation in there somewhere?
- SpikeGronim 15y agoNo, it is a DNS RFC standard behavior: http://stackoverflow.com/questions/3829966/cname-for-top-level-domain http://stackoverflow.com/questions/3829966/cname-for-top-lev...
- deleted 15y ago[deleted]
- mseebach 15y agoA records are name-to-IP, CNAME are name-to-name. When you control everything, you're right, no big deal. But in this case, customers control the DNS and Heroku the servers. Using CNAME to point to an A record at Heroku allows them to decide what IP the traffic goes to. If you use an A record, Heroku is SOL if they need the traffic to go to a new IP. Posterous has a similar problem last august. They urgently needed to change to a new IP, but all their clients were setup with A-records. Painful.
- ez77 15y ago...Heroku is SOL if they need... Off topic, what's the meaning of SOL in this context?
- Duff 15y ago"Shit Out of Luck"
- bmunro 15y ago'Square out of luck'?
- telemachos 15y agoI'm pretty sure the parent is right that it's "shit out of luck". I knew it as a military thing, and the internet seems to agree[1]. [1] http://www.etymonline.com/index.php?term=S.O.L http://www.etymonline.com/index.php?term=S.O.L. (one random link)
- mikey_p 15y agoIn polite circles it can also be "Sorry, Out of Luck"
- jwr 15y agoOk. So I'm correct in thinking that for my own domains that I manage it boils down to the same thing, e.g. there is no reason to prefer www CNAMEs over domain A records. Just wanted to check if I'm missing something.