Good

Just 198.0.103.1 in a sentence.
An IP (198.0.103.2) can be in parentheses.
Here is a sentence. 198.0.103.3, and the IP is followed by a comma.
Here is a sentence, 198.0.103.4. That sentence ended with a full stop.
Sometime markdown `198.0.103.5` is also used.
Or [198.0.103.6]
Or 198.0.103.7!

Bad

Or _198.0.103.8_
Some198.0.103.9text
!198.0.103.10!