IP Numbers

[Barry Margolin]

In article <abhaa7$ccnb$1 at isrv4.isc.org>,
Jeff Grossman  <jeff at grossman.name> wrote:
>I always see references to IP blocks at 127.0.0.0/24 or 127.0.0.0/16.  What
>do the last two digits after the "/" mean?

The number of bits in the address that represent the network portion,
versus the host portion.  /24 is equivalent to a 255.255.255.0 network
mask, while /16 is equivalent to 255.255.0.0.

>Can somebody point me somewhere where I can find this information out?

It was probably introduced in the RFC 1519, which introduced CIDR
(Classless Inter-Domain Routing).

-- 
Barry Margolin, barmar at genuity.net
Genuity, Woburn, MA
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