[dns-operations] about the underline in hostname

[Jim Reid]

On 29 May 2014, at 18:56, wbrown at e1b.org wrote:

> Out of curiosity, where did the prohibition of underscores in host names 
> come from.  I'm sure there's a historical reason for it, but I've never 
> heard it.  Or is it really as simple as "RFC 952 only listed thirty seven 
> characters"

I believe this was a limitation of the (pre?) NCP-era ARPANET and may well have been a side-effect of the capabilities of operating systems from that era. See RFCs 226 and 229.