alt Hacker NewsI don't understand why the author doesn't consider load balancing and failover legitimate use cases for low ttl. Cause it wrecks their argument?
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Why do you need a low ttl for those? You can add multiple IPs to your A/AAAA records for very basic load balancing. And DNS is a pretty bad idea for any kind of failover. You can set a very low ttl, but providers might simply enforce a larger one.
Perhaps as most these days are using Anycast [1] to do failovers. It's faster and not subject to all the oddities that come with every application having its own interpretation of DNS RFC's most notably java and all its work-arounds that people may or may not be using and all the assorted recursive cache servers that also have their own quirks thus making Anycast a more reliable and predictable choice.
Probably an expectation for floating IPs for load balancing instead of DNS.
Relatively simple inside a network range you control but no idea how that works across different networks in geographical redundant setups
Because unless your TTL is exceptionally long you will almost always have a sufficient supply of new users to balance. Basically you almost never need to move old users to a new target for balancing reasons. The natural churn of users over time is sufficient to deal with that.
Failover is different and more of a concern, especially if the client doesn't respect multiple returned IPs.