Up and running

[Antonio]

If the Internet is down, for example, and back on. Can I say "The Internet is up", "The Internet is up and running" or "The Internet is back on". These three phrases are ok or not? In a car example, can I say "The car is back on" or "The car is up and running"

If these phrases don't make any sense to you, if they are wrong, or If we're missing some other possible phrases, please let me know.
__________________
Thanks in advance,
Antonio.

[twostep]

If the Internet is down, for example, and back on. Can I say "The Internet is up", "The Internet is up and running" or "The Internet is back on". These three phrases are ok or not? In a car example, can I say "The car is back on" or "The car is up and running"

If these phrases don't make any sense to you, if they are wrong, or If we're missing some other possible phrases, please let me know.
__________________
Thanks in advance,
Antonio.

You can use "up and running", "back up" and "back on" when refering to the Internet or anything related such as a program of any kind.

You can say a car is "running", an engine is "running" or "back on track".