Why are viruses on the border between living and non living

Below.

Explanation:

They have DNA and can reproduce, but they are considered non-living because they can't reproduce without the assistance of a host cell. They also do not take the typical cell division approach when it comes to reproducing.

Hope this helps.

Resources:

https://scienceline.ucsb.edu/getkey.php?key=3316

the generally accepted parts of modern cell theory include: all known living things are made up of one or more cells. all living cells arise from pre-existing cells by division. the cell is the fundamental unit of structure and function in all living organisms.