Why are single letter domain names not allowed?

[Kelvin Chu]

I guess the poster might mean single letter domains ending with com, net
or something?

eg:
% whois e.com

IANA Whois Service
Domain: e.com
Name: IANA_RESERVED

On Tue, May 17, 2005 at 12:32:56PM +0200, Stephane Bortzmeyer wrote:
> On Sat, May 14, 2005 at 11:56:58AM -0500,
>  Dan J.S. <me at hyperx.com> wrote 
>  a message of 5 lines which said:
> 
> > Anyone know why single letter domain names are not allowed?
> 
> They are allowed. Nothing in RFC 1034 prevents them, not even
> "3.5. Preferred name syntax".
> 
> BIND has no problem:
> 
> May 17 12:31:55 myriam named[1071]: zone x/IN: loaded serial 2004122101
> 
> % dig @localhost AXFR x
> 
> ; <<>> DiG 9.3.1 <<>> @localhost AXFR x
> ; (1 server found)
> ;; global options:  printcmd
> x.                      86400   IN      SOA     ...
> ;; Query time: 23 msec
> ;; SERVER: 127.0.0.1#53(127.0.0.1)
> ;; WHEN: Tue May 17 12:32:22 2005
> ;; XFR size: 6 records (messages 1)
> 
>