I'd already looked into using the following which I think I'm right in saying is fundamentally the same as your code snippet suggestion (unless of course yours forces BIND in which case perfect!):

$hostname = gethostbyaddr( inet_aton($ip), AF_INET );
[download]

But unfortunately gethostbyaddr by design searches the sources listed in /etc/nsswitch.conf or similar.

For me this is undesirable as my single source of truth for the FQDN is not the client but DNS. With /etc/nsswitch.conf set to local followed by bind the query is likely to resolve from /etc/hosts first which cannot be relied upon to be accurate.

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

Outside of code tags, you may need to use entities for some characters:

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.