ISP inbound failover without BGP

Sebastian Spies s+Mailinglisten.nanog at
Tue Mar 4 14:16:19 UTC 2014

Am 04.03.2014 05:19, schrieb William Herrin:

> Reasons why dynamic DNS fails to perform as expected include:
> * Web browser DNS pinning can result in a customer's web browser
> holding the old IP address indefinitely.
> * Host-level caching of looked up names which discards the TTL.
> Remember: your desktop or laptop performs lookups against multiple
> name services, e.g. DNS, /etc/hosts, lmhosts, NIS+. DNS TTL is no
> longer in scope once the name to address map enters the generic host
> lookup mechanism. Most OSes have a fixed timeout of one sort or
> another, some old ones as long as 24 hours.

* Eyeball ISPs' DNS resolvers might tamper with TTL values.


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