Google says,

Chroot is an operation that changes the apparent root directory for the current running process and their children. A program that is run in such a modified environment cannot access files and commands outside that environmental directory tree. This modified environment is called a chroot jail.

Well, you can activate network support (dhcp, or internet whatever) inside a chroot jail environment.

Let's analyze a common chroot setup. I assume that I need to create a chroot jail environment at /media/kubuntu which is a root partition of a Kubuntu setup.

This would be the series of commands to mount essential paths.

DEVICE=/dev/sda1
MOUNTPATH=/media/kubuntu

mkdir -p $MOUNTPATH
mount -t auto -o acl $DEVICE  $MOUNTPATH
mount --bind /dev $MOUNTPATH/dev
mount --bind /tmp $MOUNTPATH/tmp
mount --bind /proc $MOUNTPATH/proc
mount --bind /sys $MOUNTPATH/sys

Before executing chroot, run the following command.

# do this after connecting to internet
mount --bind /etc/resolv.conf $MOUNTPATH/etc/resolv.conf
chroot $MOUNTPATH

This will bind resolve configuration inside chroot environment also. Then execute chroot.

chroot $MOUNTPATH

Do a ping inside chroot shell. Does it work or not? ;)