What segment is used by default in x86 indirect addressing?

Question

I'm a little confused as to exactly what segment is used when you have x86 assembly like the below (Intel syntax):

mov ax, [di]

I'm pretty certain it wouldn't be the code segment, I'm thinking either the data segment or the stack? (Or is the stack part of the data segment?)

Answer 1

DS is the default, except with BP indexing then SS is used. This exception is to ease the use of a stack frame (ENTER/LEAVE instructions). The string instructions have specific segment usage as well.