http-stats:
HTTP/1.1 X-Pad header field

The X-Pad field is NOT a standard HTTP header field and may not be supported by all clients.

Apache send this header to deal with a bug with Netscape versions 2 through 4.0b2.
This Netscape bug would make the client hang under certain conditions.
This Apache fix is from April of 1997. You can see the fix explaination here.


Common X-Pad header values:

The non-standard "X-Pad" header is only sent by:

NOTE: this header may be sent directly by the server software or from some third party application running on that server.

Sample X-Pad web server response:

HTTP/1.1 200 OK
Content-Type: text/html; charset=UTF-8
Content-Length: 2593
X-Pad: avoid browser bug
Date: Tue, 09 Feb 2010 02:20:05 +0000

<!DOCTYPE html PUBLIC "-//W3C//DTD ...
...
...

Other common HTTP headers

Other less common headers