Are you asking if you should update your 2.2.11 servers too or are you asking what is the oldest version you could update to and still resolve the problem?
I would guess that almost everyone here will tell you to upgrade to the newest version on all your systems. Older versions may have security issues or other bugs that are fixed in newer versions.

On Fri, Feb 6, 2015 at 3:35 PM, mahendra babu <mahi.babu@gmail.com> wrote:
Hi,

We'd filed a bug 57538 with Apache few days ago where we had impersonation issue using mod_cache in Apache 2.2.3 64-bit version.

We got reply from Apache that mod_cache bugs was fixed in 2.2.13 version and they recommended to use latest 2.2.29. 

In our environment, there are many more other apache instances but different versions 2.2.11 with mod_cache enabled. 

Before we would recommend our applications teams to use specific apache server with mod_cache enabled, we would like to know which specific base version of Apache has all mod_cache fixes?

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Thanks,
Mahendra.