Capitalization of questions in sentences

Question

Which of the following are correct:

"Tom, do you like fishing?"

"Tom, Do you like fishing?"

Answer 1

Since your example is a single sentence, your first example

Tom, do you like fishing?

is correct, if you reformulated your second example

Tom asked, "Do you like fishing?"

Capitalisation can be a question of style, but usually capitalisation occurs at the beginning of sentences and proper names.

This is an example sentence.
The Kingdom of Feedonia

It can also begin in an embedded quote within a sentence (your second example)

William asked "Where are we?"