[dns-operations] about the underline in hostname

Jim Reid jim at rfc1035.com
Thu May 29 18:30:58 UTC 2014

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.

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