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What will Route53 do if client ip matches multiple CIDR blocks in different CIDR Locations?


I haven't found behavior of Routing policy IP-based that a client ip matches 2 or more CIDR blocks in different CIDR Locations.

For an example, domain:

Record NameRouting PolicyCIDR LocationEntry Value

and we have 2 CIDR Locations in CIDR Collection

CIDR LocationCIDR Blocks

Question: When the client (ip trys to resolve, what result will he get?

2 Answers

Not sure what you meant by: "CIDR-Location-1 contains CIDR Block CIDR-Location-1 contains CIDR Block" You will just have spanning your VPC, so...

As for "Record 1:, CIDR-Location-1, A record to Record 2:, CIDR-Location-2, A record to" You configure your DNS with multiple A records for the same FQDN - the requests would get served in round-robin.

answered a month ago

I see you added more input/clarification. Here is what I tested:

  • 2 separate VPC in us-east-1 (one with and the other with
  • Created a Private hosted zone and associated with the 2 VPC above.
  • Spun 2 hosts in each of the VPC with manual assigned IP (.10)
  • nslookup and response was served in round robin, sometime getting the same IP.
answered a month ago

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