Where is the result of the "apt-get update" package list stored

I have 20 to 3o computers on my network and I have a copy of the debian packages on /var/cache/apt/archives but when I take this downloaded copy to any other machine I need to hit an "apt-get update" , How do I avoid this ? Where is the list of packages which is updated by that command stored. I need to copy them as well, and use it on a computer which is completely offline.