1 00:00:00,210 --> 00:00:09,210 So these are the private IP addresses, 10 is a class A, example, 172.16 to 172.31 is a class B and 2 00:00:09,210 --> 00:00:11,800 the 192.168 range is a class C. 3 00:00:12,360 --> 00:00:16,170 Now, don't forget, there are public IP addresses in those ranges. 4 00:00:16,620 --> 00:00:21,930 So 1 to 9 and 11 to 126 are public class addresses. 5 00:00:22,530 --> 00:00:34,590 These are examples of Class B public addresses, 128 to 172.15 and then 172.32 to 191.255.255.255 6 00:00:34,830 --> 00:00:42,550 and then class C is 192 to 192.167 and 192.169 to 223.255. 7 00:00:42,960 --> 00:00:50,130 So based on RFC 1918, some Class B and some Class C addresses were allocated for private addresses. 8 00:00:50,850 --> 00:00:56,910 Now, public addresses used to be managed by the INTERNIC, but they have been succeeded by the IANA 9 00:00:57,120 --> 00:00:59,250 or Internet assigned numbers authority. 10 00:00:59,790 --> 00:01:06,600 The IANA manages the remaining supply of IP addresses to try and ensure that IP address depletion is 11 00:01:06,600 --> 00:01:08,190 pushed out as long as possible. 12 00:01:08,580 --> 00:01:13,890 But these days, you may struggle to get IP version for public addresses as parts of the world have 13 00:01:13,890 --> 00:01:14,750 already run out. 14 00:01:15,600 --> 00:01:19,020 So who's in charge of IP addresses in different parts of the world? 15 00:01:19,290 --> 00:01:20,550 Here are some examples. 16 00:01:20,970 --> 00:01:28,020 So the IANA allocates public IP addresses to one of these groups as an example, RIPE are incharge of 17 00:01:28,020 --> 00:01:29,450 IP addresses in Europe. 18 00:01:30,720 --> 00:01:33,750 For the CCNA course, you need to know three types of NAT, 19 00:01:34,530 --> 00:01:35,760 the first one is Static Nat, 20 00:01:36,240 --> 00:01:37,880 Second one is Dynamic NAT 21 00:01:38,250 --> 00:01:39,600 and third one is PAT. 22 00:01:40,720 --> 00:01:47,620 Now, static NAT maps, a private IP version 4 address to a public IP version 4 address, this 23 00:01:47,620 --> 00:01:48,920 is a one to one mapping. 24 00:01:49,720 --> 00:01:54,870 This is very useful when a device must be accessible from outside the network. 25 00:01:55,420 --> 00:02:02,320 For example, you have a Web server in your internal network that needs to be accessible from devices 26 00:02:02,320 --> 00:02:03,000 on the Internet. 27 00:02:03,670 --> 00:02:11,560 So this type of NAT is often used for servers that require a static IP address, Dynamic NAT maps, 28 00:02:11,560 --> 00:02:19,000 a private IP version 4 address to a public IP version 4 address from a group of public IP version 29 00:02:19,000 --> 00:02:22,210 4 address or from a pool of addresses. 30 00:02:23,080 --> 00:02:28,720 This could be used as an example where two companies merge and they're using the same IP address space. 31 00:02:29,620 --> 00:02:37,000 So you have two companies, for example, using IP addresses, 10.1.1.0 and the devices in those 32 00:02:37,000 --> 00:02:42,130 two companies need to talk to each other rather than renumbering your addresses. 33 00:02:43,080 --> 00:02:47,190 You can use Dynamic NAT to allow those devices to talk to each other. 34 00:02:47,670 --> 00:02:52,350 It's not very efficient and should only be used when absolutely necessary. 35 00:02:52,950 --> 00:02:58,770 Now port address translation or PAT maps, multiple private IP addresses to a single public IP address. 36 00:02:59,520 --> 00:03:05,250 So in other words, you're taking many IP addresses and mapping them to a single public IP address. 37 00:03:05,850 --> 00:03:07,100 Think of your network at home. 38 00:03:07,470 --> 00:03:15,780 You may have multiple PCs, iPhones, iPads or other devices that all need to access the Internet. 39 00:03:17,070 --> 00:03:24,030 ISPs, however, will typically only give you one IP address for your home network, so you may have 40 00:03:24,030 --> 00:03:33,050 three or four or maybe even more devices, let's say 10 IP devices that are using one public IP address. 41 00:03:33,630 --> 00:03:39,780 So 10 devices or or as many devices as you've got at home are using private IP addresses. 42 00:03:40,140 --> 00:03:43,950 And those addresses are then NATTED to the public IP address on your router. 43 00:03:44,610 --> 00:03:49,170 This uses port numbers to differentiate between the different translations, 44 00:03:49,530 --> 00:03:51,530 hence the term port address 45 00:03:51,540 --> 00:03:55,230 translation, PAT is also known as NAT overloading. 46 00:03:55,500 --> 00:04:00,410 We are overloading a single IP address with multiple IP addresses. 47 00:04:00,870 --> 00:04:08,130 It's a type of dynamic NAT and is the most common type of NAT in use today and you'll typically find 48 00:04:08,130 --> 00:04:11,340 it all over the place in businesses as well as your home network.