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Re: dns and software, was Re: Reliable Cloud host ?
From: William Herrin <bill () herrin us>
Date: Mon, 27 Feb 2012 18:50:27 -0500

On Mon, Feb 27, 2012 at 3:43 PM, david raistrick <drais () icantclick org> wrote:
On Mon, 27 Feb 2012, William Herrin wrote:
In some cases this is because of carelessness: The application does a
gethostbyname once when it starts, grabs the first IP address in the
list and retains it indefinitely. The gethostbyname function doesn't
even pass the TTL to the application. Ntpd is/used to be one of the
notable offenders, continuing to poll the dead address for years after
the server moved.

While yes it often is carelessness - it's been reported by hardcore
development sorts that I trust that there is no standardized API to obtain
the TTL...  What needs to get fixed is get[hostbyname,addrinfo,etc] so
programmers have better tools.

Meh. What should be fixed is that connect() should receive a name
instead of an IP address. Having an application deal directly with the
IP address should be the exception rather than the rule. Then, deal
with the TTL issues once in the standard libraries instead of
repeatedly in every single application.

In theory, that'd even make the app code protocol agnostic so that it
doesn't have to be rewritten yet again for IPv12.

Regards,
Bill Herrin

-- 
William D. Herrin ................ herrin () dirtside com  bill () herrin us
3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
Falls Church, VA 22042-3004


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