Metric on two pointic set

Question

Find all metric on a set $X$ consisting of two points.

Obviously there is discrete metric $d$. And $kd$ ($k>0$) is also metric.

Can there any other metric be given?

Edit :

What can you say when $X$ is any finite set?

Answer 1

No. If the set is $\{a,b\}$ ($a \neq b$) with metric D then $D(a,b)$ is some positive number $c$. This makes $D$ equal to $c$ times the discrete metric.