I have bought a Ultrabook and found that normal cables for LAN are not suitable for it.
There is a slot which seems to be for cables, but the height is too low.
What is the slot? What kind of cable should I buy?
It is still the same, a normal RJ-45 plug:
As ultrabooks are much thin that a normal notebook, the female connector looks like smaller, a normal female RJ45 plug just wouldn`t fit on the ultrabook depth, so a mobile part was added with a spring that hold the male connector into the female. If you pull down the mobile part you will notive that is still the same.