dns and software, was Re: Reliable Cloud host ?

William Herrin bill at herrin.us
Mon Feb 27 23:50:27 UTC 2012

On Mon, Feb 27, 2012 at 3:43 PM, david raistrick <drais at 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.

Bill Herrin

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

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