I am seeing lots of logs on the eventlog indicating "ISTAG change." What is ISTAG? Is this a problem?

Products

• ProxyAV Software - AVOS
• ProxySG Software - SGOS

Issue/Introduction

 Every response from an ICAP v1.0 server must contain an ISTag value that indicates the current state of the ICAP server.

For instance, when the pattern/scanner version of a virus scanner on the ICAP server changes, the ISTag value changes. This change invalidates all content cached with the previous ISTag value, and a subsequent request for any content in cache must be refetched from the original content server and scanned by the ICAP server.

Eventlog indicating "ISTAG change" is common, and not considered a problem.