Nether rail, wich altitude (height)

On wich height is it safe to build a nether rail or tunnel ?

the higher the better in my opinion

In the ceiling of the nether where the bedrock is right above your head is pretty great, or at the way bottom where the bedrock floor is. Both ways avoid lava lakes and briefers

Ok. Wich height is the ceiling and wich one the bottom ? its count from 0 to ?

y:5 is probably your best bet

The ceiling is at y 128, so you could build a few blocks below that.

I make all of mine at y:5.
{EDIT} ninja'd -_-

The nether goes from y=1 (standing on the lowest possible block) to y=128 (standing on the highest layer of bedrock). There are 5 layers of bedrock at both heights, so if you're building at the bottom, you want your feet position to be y=5. If you're building at the top, I'd think you'd want y=121. I recommend building at y=5 since tunnels at this height can't bee seen from livemap.

Now understand the nether, did some more things tonight. got in bad position for while. but now i can calculate etc. the coordinates to.