When I execute `apt update`, apt will update the file on the website listed in `/etc/apt/sources.list` to local, for example, <http://cn.archive.ubuntu.com/ubuntu/dists/xenial/main/binary-amd64/Packages.gz>, apt update will download this file to local(/var/lib/apt/lists). this file describes the dependencies of the deb package.

Does the old version of this file exist on the website?

Thanks in advance!