I got 1 interesting question from Yee, humm... might be a killer question, the 1 that I can't answer,hehe
Yee: We are talking about IPv4 and the new IPv6... whare is IPv 1,2 & 3??? Then where is IPv5???
Faizal: haha... (blank, I don't know)
Ok guys, now I have the answers.... haha, it's very interesting and I think that there are many CCNAs out there not aware about this...
The IP defined in RFC 791 was the first widely-used version of the Internet Protocol. RFC mean Request for Comments is a memorandum published by the Internet Engineering Task Force (IETF) describing methods, behaviors, research, or innovations applicable to the working of the Internet and Internet-connected systems.
Interestingly, however, it is not version 1 of IP but version 4! This would of course imply that there were earlier versions of the protocol at one point. Interestingly, however, there really weren't. As I mentioned above, IP was created when its functions were split out from an early version of TCP that combined both TCP and IP functions. TCP evolved through three earlier versions, and was split into TCP and IP for version 4. That version number was applied to both TCP and IP for consistency. Even though the name seems to imply that it's the fourth iteration of the key Internet Protocol, version 4 of IP was the first that was widely used in modern TCP/IP.
A natural question at this point of course is: what happened to version 5 of IP? The answer is: it doesn't exist. While this may seem confusing, version 5 was in fact intentionally skipped to avoid confusion, or at least to rectify it. The problem with version 5 relates to an experimental TCP/IP protocol called the Internet Stream Protocol, Version 2, originally defined in RFC 1190. This protocol was originally seen by some as being a peer of IP at the Internet Layer in the TCP/IP architecture, and in its standard, these packets were assigned IP version 5 to differentiate them from “normal” IP packets (version 4). This protocol apparently never went anywhere, but to be absolutely sure that there would be no confusion, version 5 was skipped over in favor of version 6.
More info at: http://www.tcpipguide.com/