Why the difference between network addresses reported by hostname and ping

From man ping:

   -w deadline
          Specify a timeout, in seconds, before ping exits regardless of how many packets have been sent or received. In this case ping does not stop after count packet are sent, it waits either for deadline expire or until count probes are answered or for some error
          notification from network.

   -W timeout
          Time to wait for a response, in seconds. The option affects only timeout in absense of any responses, otherwise ping waits for two RTTs.

That is, -w sets the timeout for the entire program session. If you set -w 30, ping (the program) will exit after 30 seconds.

-W on the other hand sets the timeout for a single ping. If you set -W 1, that particular ping attempt will time out.

As for how to set an individual ping timeout of 200ms, I don't believe this can be done with iputils' version of ping. You might want to try directly programming with an ICMP library.

hostname returns the configured hostname or nodename. In practice, it can either be a short name (in most configurations) or a long name (normally the FQDN in this case). The short name is given by hostname --short.

hostname --fqdn returns the FQDN, which is gethostbyname on the nodename (as returned by the uname system call, see uname(2) man page).

hostname -A is something obscure and non-intuitive. In particular, despite its name and description ("all FQDNs"), it doesn't give the standard FQDN, by design. Thus I would say: do not use it. One reason is that it misses valid IP addresses of the machine, such as 127.0.1.1, with which the FQDN may be associated in the /etc/hosts file (this is currently the default under Debian and Ubuntu, for instance). Another issue with the hostname -A method is that the reverse resolution of an IP address doesn't necessarily give a FQDN; it can just be a short name.

Concerning your problem with python, it may be a bug there. I don't know. I suggest that you try the following Perl script:

#!/usr/bin/env perl

use strict;
use POSIX;

my $nodename = (POSIX::uname)[1];
print "Nodename: $nodename\n";

my @ghbn = gethostbyname $nodename;
print "FQDN: $ghbn[0]\n";

$ghbn[0] !~ /\./ && $ghbn[1] =~ /(\S+\.\S+)/
  and print "Fixed FQDN from aliases: $1\n";