 it is safe to reuse the <code>buf</code> object.
DNS lookups delay the time to send for at least one tick of the
Node.js event loop.</p>
<p>The only way to know for sure that the datagram has been sent is by using a
<code>callback</code>. If an error occurs and a <code>callback</code> is given, the error will be
passed as the first argument to the <code>callback</code>. If a <code>callback</code> is not given,
the error is emitted as an <code>'error'</code> event on the <code>socket</code> object.</p>
<p>O