pr#190: document expense of identitycheck

Reviewed by:
Submitted by:
Obtained from:

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@77767 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/docs/manual/mod/core.html b/docs/manual/mod/core.html
index 8a669e14160939c6969bca1bed6b5277188ce556..04fe22dee46e7ef5d6f87cedc80db3679855622a 100644 (file)
--- a/docs/manual/mod/core.html
+++ b/docs/manual/mod/core.html
@@ -529,7 +529,14 @@ This information is logged in the access log. <em>Boolean</em> is either
 <code>on</code> or <code>off</code>.<p>
 
 The information should not be trusted in any way except for rudimentary usage
-tracking.<p><hr>
+tracking.<p>
+
+Note that this can cause serious latency problems accessing your server
+since every request requires one of these lookups to be performed.  When
+firewalls are involved each lookup might possibly fail and add 30 seconds
+of latency to each hit.  So in general this is not very useful on public
+servers accessible from the internet.
+<p><hr>
 
 <A NAME="ifmodule"><H2>&lt;IfModule&gt;</H2></A>
 <b>Syntax:</b> &lt;IfModule [!]<i>module-name</i>&gt; <i>...</i>