[MIT-Scheme-devel] Re: DNS queries, blocking C calls, and non-file-descriptor events

[Taylor R Campbell]

   Date: Tue, 08 Aug 2006 18:33:27 -0500
   From: James Graves <address@hidden>

   In 2006, it is my opinion that if you aren't using DNS for hostname 
   resolution, you're doing it wrong.  So, again in my opinion, I'd just do 
   DNS lookups directly.

The issue is not that DNS isn't used *somewhere*, but different
operating systems have different ways to configure it and the
particular servers to use and so on, and I can't reasonably go through
every single one of these to determine the proper DNS queries to send
to the proper locations, when applicable.  For example, OS X pays no
attention to /etc/hosts and /etc/resolv.conf; instead it stores the
equivalent information in NetInfo, and name resolution queries go
through lookupd.  The situation is entirely different on Linux and
different still on Solaris.

Doing DNS lookups is not the hard part, except for the issue with I/O
selection that I brought up recently, even if it may be tricky to do
correctly here.  Parsing *one* operating system's name service
configuration files is not hard.  Doing it for the general case, for
any operating system that Scheme runs on (even if all we assume is
POSIX, or some subset thereof), is the hard part.