[dns-operations] Link-local IP addresses for a resolver?

John R Levine johnl at taugh.com
Tue Sep 24 23:52:32 UTC 2019

On Wed, 25 Sep 2019, Mark Andrews wrote:

> ISP’s advertings ULA’s to customers have similar problems with 
> advertising LLL to customers. The CPE should be the site boundary making 
> the ISP’s DNS servers unreachable from inside the customer’s network.

> DNS servers that are expected to be reached across sites need to be 
> globally unique addresses which ULA and LL are not.

If a ULA isn't globally unique, something is pretty broken.  Each ULA 
contains a 40 bit random global ID in the prefix that's there so ULAs on 
different networks won't collide if they happen to be connected.  That's 
why the U stands for, you know, Unique.

John Levine, johnl at taugh.com, Taughannock Networks, Trumansburg NY
Please consider the environment before reading this e-mail. https://jl.ly

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