Can I install Debian packages from Stretch DVD 2 and 3 after installation using apt? Because installing on VM, it didn't detect the second and the third DVD.
/etc/apt/sources.list you will have an entry like this for the first DVD after installation:
deb cdrom:[Debian GNU/Linux 9.8.0 "Stretch" - Official amd64 DVD Binary-1 20190216-11:59]/ stretch contrib main
This line is used to tell apt to use the cdrom as a package source.
The second and third DVD should be "Binary-2" and "Binary-3". The complete string can be found on the DVD in the file
If you only have the ISO files and no (virtual) optical drive is available,
you can mount the images manually and add a
deb file: source to