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I know that anycast will failover for layer 3 issues but will anycast failover if a file is not present? I.E. like a 404?

It seems like it won't, like as long as nginx returns something anycast will consider that server healthy.

user970705
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    Not only that. 404 is a valid answer and should by logic be returned by all servers. it indicates a URL with nothing behind, not any kind of infrastructure failure, which anycast is there to handle. There are a lot of scenarios where all kinds of HTTP level error codes are valid returns. – TomTom Oct 17 '22 at 14:24
  • Awesome that's what I though. Thanks for the info. – user970705 Oct 17 '22 at 14:28

1 Answers1

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I know that anycast will failover for layer 3 issues but will anycast failover if a file is not present? I.E. like a 404?

Neither nor. Anycast presents a specific IP address at multiple points in the network. When the currently routed destination is unavailable or broken, then that's it.

All the client could do is send another, identical request. Unless there's some way that the network itself fails over in the meantime (esp. anycast routing removing the faulty destination), that won't yield a different result.

If you had another scheme with a DNS hostname with multiple A records behind it, then the client could attempt a connection to one of the other IP addresses when the first attempt failed on the transport-protocol level. That is implementation specific and not a given though. In any case, if the contacted server connects and replies - even with a 404 - then the client won't attempt anything else.

Zac67
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