On 12/22/2019 3:13 PM, Keith Moore wrote:
Of course, SMTP predates DNS, and was designed at a time when DNS didn't
Domains are a recently introduced concept in the ARPA Internet
mail system. The use of domains changes the address space from a
flat global space of simple character string host names to a
hierarchically structured rooted tree of global addresses.
SMTP and the DNS were developed at the same time. Work on SMTP (and RFC
822) explicitly anticipated the DNS.
In any event, email -- using the FTP mail commands -- had already relied
on use of hostnames -- ie, textual names -- for roughly a decade,
independent of the means for mapping the name to the network address.
ps. Email has been used for inter-process communications, of the sort
you cite, also since the 1970s.
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