title: Disadvantages and limitations of ETags
body: <p><code>ETags</code>, as I read about, is one of the ways to implement the <code>Caching validation</code>. We are planning to implement this on our servers.  We have 2 apaches running.  I wanted to know if there are any limitations and disadvantages in using <code>ETags</code>.  If there are no such limitation, then why ain't it being used as a simple rule in configuring one's server(s)?.</p>