Question

I use curl to request MS’ jquery cdn, and get the follow response:

C:\Documents and Settings\zhidao.it>curl http://ajax.microsoft.com/ajax/jquery/jquery-1.4.2.min.js -I
HTTP/1.1 200 OK
Cache-Control: public,max-age=31536000
Content-Length: 72413
Content-Type: application/x-javascript
Accept-Ranges: bytes
ETag: "90df7dfe29b4ca1:0"
Server: Microsoft-IIS/7.5
VTag: 79140211700000000
P3P: CP="ALL IND DSP COR ADM CONo CUR CUSo IVAo IVDo PSA PSD TAI TELo OUR SAMo CNT COM INT NAV ONL PHY PRE PUR UNI"
X-Powered-By: ASP.NET
Age: 15694
Date: Sun, 17 Apr 2011 11:16:14 GMT
Last-Modified: Tue, 23 Feb 2010 01:46:18 GMT
Expires: Mon, 16 Apr 2012 06:54:40 GMT
Connection: keep-alive

I noticed there is a strange header VTag. I have googled for it, but found nothing. What is that? and how to use it?

Answer 1

If it’s not documented on the interwebs anywhere, it’s probably used internally by MS. Possibly to do with virtual servers?

Have you seen it on other sites (non-MS ones)?