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Re: Renumbering

2007-09-19 09:15:35
Thus spake "Iljitsch van Beijnum" <iljitsch(_at_)muada(_dot_)com>
On Sep 13, 2007, at 20:52 , Keith Moore wrote:
How do you renumber the IP address stored in the struct sockaddr_in in a long running critical application?

Disconnect current session, reconnect.

Many proprietary protocols do not have the ability to checkpoint a connection and resume it on a different socket. It is not uncommon to require human intervention to retry a connection, or to have to redo all the work from scratch. It is also not uncommon for server applications to crash if their IP address is changed out from under them, or refuse to load with a new IP address.

Applications that don't respect DNS TTLs are broken for many reasons, not
just network renumbering.

Since when is it the job of applications to manage DNS TTLs?

It's not. However, many applications are coded to ask DNS once for each name and cache the result forever; this is a problem for long-lived processes, particularly servers, though it can even be seen in common web browsers. Some OSes include a caching resolver that has similar bugs. Some ISPs have caching nameservers that increase TTLs.

All of those things are broken, of course. That doesn't change the fact they exist and folks in the operational community will not be impressed with a "solution" that ignores those problems.

S

Stephen Sprunk         "God does not play dice."  --Albert Einstein
CCIE #3723         "God is an inveterate gambler, and He throws the
K5SSS dice at every possible opportunity." --Stephen Hawking


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