Easy method. Download a file from Computer A, time it. Download the same file from Computer B, time it. B download should be instantly.
Correct method. Check logs, it says if its recovered from cache (TCP_HIT) or recovered from original source (not cached, it appears as TCP_MISS).
try the command:
tail /var/log/squid/access.log -n 1000 | grep TCP_HITWill show the last cache hits.
If for example you want to check if the system is caching windows updates, try something like
cat /var/log/squid/access.log | grep TCP_HIT | grep updateYou'll get something like
Jul 6 16:05:48 efw-1111007750 squid[19054]: 1278440368.572 0 192.168.X.X TCP_HIT/200 10149 GET http://download.windowsupdate.com[....].cab - NONE/- application/octet-streamI suggest you increase the max object size in the proxy webpage to something like 100000 (100MB), or even more if you want to cache big downloads.