This is a brief overview of the ISA cache management flowchart. Web caching is more of a major development in ISA than in Proxy 2.0. It's 10 times faster. One of the main differences between the Web Proxy and ISA versus Proxy 2.0 is that the Web Proxy cache is now a hot cache in RAM versus in Proxy 2.0 where it was only on the disk. RAM is a bit more important now.

For large files, if the file is large enough to be allowed under the cache settings, then it will come from the ISA cache. The other thing to be careful of is a lot of things such as service packs now are active setups where you're running it and it's actively going out and copying things and installing them. Things like that are unlikely to be cached.

If the file is coming from an FTP server, then certainly it will cache it. If it came as an HTTP page, then it will cache it too. Nothing else will be cached. Large files such as service packs may not be cached unless the file size limitations allow such large files. The cache control settings on the Web server determine cache and behaviour.