All language subtitles for 10. RFC1918 - Private Addresses

Now RFCs or Request For Comments are formal documents

from the IETF or Internet Engineering Task Force

which are typically drafted via a committee from multiple vendors

and are reviewed by interested parties.

RFCs are intended to become Internet Standards and the final

version of an RFC will become an Internet Standard and there

often no changes are permitted to that RFC.

However changes or updates can be made in subsequent RFCs

and you'll often find this, where certain RFCs are superseded by
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other newer RFCs and therefore become obsolete
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Essentially a lot of the information that we're studying
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in networking, comes originally from RFCs or Request For Comments.
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They are important to understand and read if you want to get
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into the nitty gritty or details of specific protocols
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However, in networking one of the jokes you may hear is that
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If you can't sleep at night, go and read a bunch of RFCs
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and that's going to put you to sleep.
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However some RFCs are actually done in good humor, and there's
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even an RFC, RFC 1149 describing IP over AVIAN Carriers
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or in other words, how to transmit IP packets using pigeons
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and I am not joking, go and have a look at RFC 1149
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and you can see how it's possible to send data using pigeons.
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Obviously done in good humor.
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Now being serious for a moment, one of the famous RFCs
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that you need to know is RFC 1918.
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RFC 1918, discusses Private IP Addresses
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which are non-routable addresses on the internet these addresses
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will be blocked by Internet Service Providers or ISPs
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and can thus not be used for sending traffic unto the internet.
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So here's RFC 1918, just do a simple search in Google or your
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favorite search engine and you'll be able to find this RFC
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or go to tools.ietf.org/html/rfc1918
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As you can see here, various parties were involved
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in the drafting of this RFC, and it also obsoletes previous RFCs.
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This RFC is Address Allocation for Private Internets
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and explains best practices for the Internet Community
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with regards to Private Addressing, notice the date February 1996.
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That's a long time ago, even that many years ago
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it was recognized, that there was a problem
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with the exhaustion of IPv4 addresses
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As I'm recording this in 2015,
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the Address Registrar for the Americans has recently run out of
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IP addresses, so this RFC was created to try and increase
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longevity of IPv4 and it's actually worked quite well.
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The exhaustion of IPv4 has been postponed,
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for longer than a lot of people expected.
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In this RFC they mention some of the problems of the internet
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which are still challenges today, for example how the internet has
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has grown beyond anyone's expectations and this RFC describes the
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use of private IP addresses internally within organizations
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and those IP addresses would be NAT'd or Address Translated
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when traffic is sent unto the internet.
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Notice in the RFC, it states that the Internet Assigned
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Numbers Authority or IANA, has reserved the following blocks
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of IP address space for private internets.
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So we have network 10, which is a class A address
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networks 172.16 up to 172.31 which are class B networks and
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192.168 all the way up to 192.168.255 which are class C networks.
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They refer to CIDR in the RFC and we'll discuss CIDR in a moment
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and I'll explain what this mask mean, but essentially notice that
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a single class A network, 16 contiguous class B networks
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and 256 class C networks have been allocated for private addresses.