Sealing a toilet drain

[Blue]

I have a problem with a leak under the linoleum around a toilet. In advance of repairing it I'm wondering about the leak possibilities. I know that the wax ring is supposed to install around the waste horn with the tapered end upside and I assume squash against the drain flange and the bottom of the toilet bowl above the horn but I'm wondering about the possibility of a leak between the waste flange and mating drain pipe or even a break in the pipe. I'm going to hire a licensed plumber to fix this but I'd like to understand the problem too. Any ideas on this?

[Inspector D]

[Blue]

Just how does the waste flange attach to the mating wastepipe below? Is there a possibility of leaking there even if the wax ring is intact and not leaking?