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Welcome to brain Stuff 8 00:00:23,079 --> 00:00:34,280 Speaker 1: from how Stuff works dot com, where smart happens him 9 00:00:34,360 --> 00:00:38,320 Speaker 1: mercial brain With today's question, what is an IP address? 10 00:00:39,240 --> 00:00:42,800 Speaker 1: Every machine on the Internet has a unique identifying number 11 00:00:42,880 --> 00:00:46,560 Speaker 1: called an IP address. A typical IP address looks something 12 00:00:46,600 --> 00:00:51,440 Speaker 1: like this to sixteen dot seven dot sixty one dot 13 00:00:51,479 --> 00:00:54,400 Speaker 1: one thirty seven. It's made up of four numbers with 14 00:00:54,520 --> 00:00:57,800 Speaker 1: dots between them to make it easier for US humans 15 00:00:57,800 --> 00:01:02,400 Speaker 1: to remember. IP addresses their normally expressed in decimal format 16 00:01:02,520 --> 00:01:06,840 Speaker 1: as a dotted decimal number like this, but computers communicate 17 00:01:06,880 --> 00:01:10,319 Speaker 1: in binary form to a computer, and IP address is 18 00:01:10,400 --> 00:01:14,520 Speaker 1: just a thirty two bit binary number. To sixteen twenty 19 00:01:14,560 --> 00:01:17,040 Speaker 1: seven dot sixty one dot one thirty seven is a 20 00:01:17,120 --> 00:01:22,080 Speaker 1: representation of that thirty two bit binary form. The four 21 00:01:22,160 --> 00:01:25,959 Speaker 1: decimal numbers in an IP address are called octets because 22 00:01:26,000 --> 00:01:30,039 Speaker 1: they each have eight positions. When viewed in binary form, 23 00:01:30,080 --> 00:01:33,000 Speaker 1: if you add all the positions together, you get thirty two, 24 00:01:33,080 --> 00:01:35,480 Speaker 1: which is why I P addresses are considered to be 25 00:01:35,800 --> 00:01:39,280 Speaker 1: thirty two bit numbers. Since each of the eight positions 26 00:01:39,319 --> 00:01:42,559 Speaker 1: can have two different states, one or zero, the total 27 00:01:42,640 --> 00:01:46,640 Speaker 1: number of possible combinations per octet is two hundred fifty six, 28 00:01:47,080 --> 00:01:50,160 Speaker 1: so each octet can contain any value between zero and 29 00:01:50,200 --> 00:01:53,600 Speaker 1: two hundred fifty five. Combine the four octets and you 30 00:01:53,680 --> 00:01:57,760 Speaker 1: get about four billion unique values. Out of those four 31 00:01:57,800 --> 00:02:01,840 Speaker 1: billion possible combinations, certain values are restricted from use as 32 00:02:01,920 --> 00:02:05,680 Speaker 1: typical IP addresses. For example, the IP address zero dot 33 00:02:05,760 --> 00:02:09,000 Speaker 1: zero dot zero dot zero is reserved for the default network, 34 00:02:09,040 --> 00:02:11,840 Speaker 1: and the address to fifty five dot to dot to 35 00:02:12,560 --> 00:02:16,519 Speaker 1: dot to fifty five is used for broadcasts. The octets 36 00:02:16,560 --> 00:02:20,240 Speaker 1: serve a purpose other than simply separating the numbers. They're 37 00:02:20,280 --> 00:02:24,040 Speaker 1: also used to create classes of IP addresses that can 38 00:02:24,080 --> 00:02:27,240 Speaker 1: be assigned to a particular business, government, or other entity 39 00:02:27,360 --> 00:02:30,919 Speaker 1: based on size and need. The octets are split into 40 00:02:31,000 --> 00:02:35,280 Speaker 1: two sections, Net and host. The net section always contains 41 00:02:35,360 --> 00:02:38,880 Speaker 1: the first doctet. It's used to identify the network that 42 00:02:38,919 --> 00:02:43,040 Speaker 1: a computer belongs to. Host, sometimes referred to as node, 43 00:02:43,160 --> 00:02:46,680 Speaker 1: identifies the actual computer on the network. The host section 44 00:02:46,720 --> 00:02:51,000 Speaker 1: always contains the last doctet. When originally conceived, there was 45 00:02:51,120 --> 00:02:54,280 Speaker 1: no idea that the Internet would become so popular, But 46 00:02:54,360 --> 00:02:58,040 Speaker 1: today almost all of the four billion addresses are in use. 47 00:02:58,480 --> 00:03:01,440 Speaker 1: So there's a new standard called i p V six, 48 00:03:01,480 --> 00:03:05,040 Speaker 1: where IP addresses become a hundred and twenty eight bits long. 49 00:03:05,720 --> 00:03:09,320 Speaker 1: This number of bits should allow enough IP addresses so 50 00:03:09,360 --> 00:03:13,840 Speaker 1: that we never ever run out of them again. For 51 00:03:13,960 --> 00:03:16,360 Speaker 1: more on this and thousands of other topics, visit how 52 00:03:16,440 --> 00:03:18,760 Speaker 1: stuff works dot com and don't forget to check out 53 00:03:18,760 --> 00:03:20,680 Speaker 1: the brain stuff blog on the house stuff works dot 54 00:03:20,680 --> 00:03:23,280 Speaker 1: com home page. 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