Lookup IPv4 and IPv6 addresses for a hostname. Only prints addresses on stdout (one per line), errors to stderr, and hard errors can be detected through inspecting the exit code.

Exit codes:

• 0: success (or NODATA). You might want to treat an empty address set (no output) as failure too (similar to NXDOMAIN).
• 1: name not found (NXDOMAIN). If an empty address set is ok for you, you might want to ignore this exit code.
• 2: SRVFAIL, timeouts, failed parsing response, generic resolver failure...
• 3: failed parsing a specific answer record (might have printed partial result, but breaks on first broken record)

Other exit codes should be treated as failures too; a non-zero exit code always should show an error on stderr, and every time an error is printed to stderr there should be a non-zero exit code.