Any difference in using 169.254.169.253 vs net_addr+2 for DNS?

Question

A customer is looking into some DNS resolution issues. While reading  [AWS DNS documentation](https://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_DHCP_Options.html#AmazonDNS), I noticed that we could use either 169.254.169.253 or net_addr+2 as DNS server for EC2 instances.

This leads me to two questions:

1. If you have a network path to the 169.254.169.253 address and your
    OS allows for its usage, is there any difference in using it instead
    of the net_addr+2 server?
 2. Specifically, would using 169.254.169.253 affect DNS resolution that factors in AZ locality (e.g., EFS DNS name for file systems)?

mehrajk · Accepted Answer

Essentially using net_cidr_base+2 or 169.254..169.253 for DNS resolution with in VPC leads to the same recursive DNS resolution service. However 169.254.x.x address space ([Link Local address space][1] )  may be reserved or not allowed with in some OS (e,g Win server 2008 use case mentioned  in [AWS DNS document][2]

[1]: https://en.wikipedia.org/wiki/Link-local_address
  [2]: http://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_DHCP_Options.html

Any difference in using 169.254.169.253 vs net_addr+2 for DNS?

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