We're planning to switch our website from an A record that points to an IP address to a CNAME record that points to another site. I'm curious about how much downtime we might experience during this transition. I also think it would be wise to lower the TTL to the minimum value a few days before making the change—what do you think?
3 Answers
As long as the destination IP for the CNAME stays the same, you should be fine without any downtime. Both the old A record and new CNAME would then resolve correctly. Just bear in mind that different setups can respond variably based on whether it's an IP or hostname.
Make sure to drop the TTL to a short, reasonable time before you make the switch, and just hope that the important users will respect that setting!
If both the original and new IPs are live at the same time, your site shouldn't actually go down. Some users might hit the old IP because their DNS is cached, but this will resolve when the TTL expires. Just a heads up—some DNS servers ignore TTL settings entirely, so keep that in mind! Also, remember that using CNAMEs on root domains is generally not recommended.
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