SLD starting with digit (or containing only digits)

> I would be grateful if someone could tell me what problems could arise
> by permitting domain names starting with a digit, or even containing
> *only* digits, under a TLD.
> 
> I know this is not in accordance with RFC952. My question really is
RFC952 was updated by RFC1123, so names starting with a digit are
perfectly legal (technically). At all, we have to differentiate between
host and domain names, with the latter being very little restrictions
placed upon.
However, most domain names wrt second level domains are intended to
become (part of) hostnames.

You will have to avoid host names that could be interpreted as IP addresses.

> what technical problems could be expected if a TLD were to decide that
> it allows the above (and currently the required domain name length is only
> two characters).
I do not understand this additional restriction.

-Peter