What types of numbers may MX records use for weight?

Question

For example, could one use a real number as an MX weight? Is there a limit to how many decimal places an MX weight may have?

Answer 1

MX weight/preference/distance is transmitted as 16 bit integer (from 0 to 65535=0xFFFF).

I do not remember seeing use of MX preferences above 1_000.

RFC-1035 : 3.3.9. MX RDATA format