1 1 00:00:00,670 --> 00:00:03,030 Assigning IP addresses. 2 2 00:00:03,030 --> 00:00:04,560 Now when we have our networks 3 3 00:00:04,560 --> 00:00:07,290 and they rely on IP addresses like IPv4, 4 4 00:00:07,290 --> 00:00:08,480 how do we tell our devices 5 5 00:00:08,480 --> 00:00:10,620 what addresses they're going to have? 6 6 00:00:10,620 --> 00:00:13,110 Well, there are really two different methods we can use. 7 7 00:00:13,110 --> 00:00:15,720 One is to manually or statically assign them, 8 8 00:00:15,720 --> 00:00:18,050 and the other is to dynamically assign them. 9 9 00:00:18,050 --> 00:00:19,690 Now, when I use a static assignment, 10 10 00:00:19,690 --> 00:00:21,570 this is a really simple process. 11 11 00:00:21,570 --> 00:00:22,440 As a technician, 12 12 00:00:22,440 --> 00:00:25,250 I manually will type in the IP address for the host, 13 13 00:00:25,250 --> 00:00:27,130 its subnet mask, its default gateway 14 14 00:00:27,130 --> 00:00:28,690 and its DNS server. 15 15 00:00:28,690 --> 00:00:31,680 But this can be time consuming and prone to error. 16 16 00:00:31,680 --> 00:00:34,680 For example, let's say I have 20 devices on the network. 17 17 00:00:34,680 --> 00:00:35,590 Now I'm going to have to go 18 18 00:00:35,590 --> 00:00:37,730 and assign those four pieces of information 19 19 00:00:37,730 --> 00:00:40,160 20 different times, once for each device, 20 20 00:00:40,160 --> 00:00:42,590 that's 80 places I have to enter information. 21 21 00:00:42,590 --> 00:00:45,400 This means there's a lot of chance for human error here, 22 22 00:00:45,400 --> 00:00:47,930 because these numbers are very easy to mistype, 23 23 00:00:47,930 --> 00:00:49,370 and if you mistype one, 24 24 00:00:49,370 --> 00:00:51,080 you're going to be assigning the wrong information 25 25 00:00:51,080 --> 00:00:52,400 to the wrong devices. 26 26 00:00:52,400 --> 00:00:55,970 Or you might have the same information on multiple devices. 27 27 00:00:55,970 --> 00:00:57,460 And this will also cause problems 28 28 00:00:57,460 --> 00:00:59,610 or conflicts between two devices. 29 29 00:00:59,610 --> 00:01:02,770 So as you start to work on large enterprise networks, 30 30 00:01:02,770 --> 00:01:05,400 it becomes very impractical to do static assignment 31 31 00:01:05,400 --> 00:01:08,070 of the IP addresses for all your devices. 32 32 00:01:08,070 --> 00:01:10,010 Some of our networks in the past that I've run 33 33 00:01:10,010 --> 00:01:12,550 have been 500 clients, 1,000 clients, 34 34 00:01:12,550 --> 00:01:14,487 5,000 clients, 10,000 clients, 35 35 00:01:14,487 --> 00:01:18,450 100,000 clients, or even 1 million client computers 36 36 00:01:18,450 --> 00:01:20,210 in a large-scale intranet. 37 37 00:01:20,210 --> 00:01:22,360 So for us to assign those all statically 38 38 00:01:22,360 --> 00:01:24,670 and keep track of all of those different IP addresses, 39 39 00:01:24,670 --> 00:01:26,330 would become a full-time job 40 40 00:01:26,330 --> 00:01:27,710 for a large team of people 41 41 00:01:27,710 --> 00:01:29,180 located at all over the world 42 42 00:01:29,180 --> 00:01:31,970 because that large intranet spans six continents. 43 43 00:01:31,970 --> 00:01:33,810 That would be a waste of a lot of time, 44 44 00:01:33,810 --> 00:01:36,240 money, labor, and resources. 45 45 00:01:36,240 --> 00:01:39,020 So instead we, simplify this process 46 46 00:01:39,020 --> 00:01:41,830 by using dynamic allocation of IP addresses. 47 47 00:01:41,830 --> 00:01:44,070 This is known as a dynamic assignment. 48 48 00:01:44,070 --> 00:01:45,940 By doing this, we have a quicker, 49 49 00:01:45,940 --> 00:01:49,070 easier and less confusing method of assigning our IPs 50 50 00:01:49,070 --> 00:01:51,960 to all of our network clients when they join the network. 51 51 00:01:51,960 --> 00:01:53,770 Now for larger small networks, 52 52 00:01:53,770 --> 00:01:55,130 using dynamic IP addressing 53 53 00:01:55,130 --> 00:01:57,580 is usually going to be your best option. 54 54 00:01:57,580 --> 00:01:59,570 In your home, whether or not you know it, 55 55 00:01:59,570 --> 00:02:02,320 you're already probably using dynamic IP addressing. 56 56 00:02:02,320 --> 00:02:04,320 When you bought a new smartphone or tablet 57 57 00:02:04,320 --> 00:02:05,710 or laptop or desktop, 58 58 00:02:05,710 --> 00:02:07,710 you took it out of the box, you powered it on, 59 59 00:02:07,710 --> 00:02:09,400 and then you joined your wireless network, 60 60 00:02:09,400 --> 00:02:11,960 and you were able to go online and browse the web, right? 61 61 00:02:11,960 --> 00:02:14,330 You didn't have to do any kind of crazy configurations. 62 62 00:02:14,330 --> 00:02:15,330 Well, in this case, 63 63 00:02:15,330 --> 00:02:17,880 you didn't assign your new device an IP address, 64 64 00:02:17,880 --> 00:02:19,600 a subnet mask, a default gateway, 65 65 00:02:19,600 --> 00:02:21,320 or a DNS server to use. 66 66 00:02:21,320 --> 00:02:23,440 Instead, your network's DHCP server 67 67 00:02:23,440 --> 00:02:25,180 did all that for you automatically, 68 68 00:02:25,180 --> 00:02:27,240 without you even having to ask it to. 69 69 00:02:27,240 --> 00:02:28,760 This is because most small office 70 70 00:02:28,760 --> 00:02:31,360 and home office network devices like your cable modem, 71 71 00:02:31,360 --> 00:02:33,490 fiber modem, or wireless access point 72 72 00:02:33,490 --> 00:02:35,970 already have a running DHCP server there for you 73 73 00:02:35,970 --> 00:02:37,750 and it's turned on by default. 74 74 00:02:37,750 --> 00:02:39,810 You just tell the device what network to join 75 75 00:02:39,810 --> 00:02:41,380 and your router will use DHCP 76 76 00:02:41,380 --> 00:02:43,160 to hand out a dynamic IP address 77 77 00:02:43,160 --> 00:02:45,520 for your network client to be able to utilize. 78 78 00:02:45,520 --> 00:02:47,370 So what are those four components 79 79 00:02:47,370 --> 00:02:48,960 of a fully configured client? 80 80 00:02:48,960 --> 00:02:50,570 Well, I've said it a couple of times, 81 81 00:02:50,570 --> 00:02:52,630 and whether you're using static or dynamic assignment, 82 82 00:02:52,630 --> 00:02:55,400 you still need to use the same four components. 83 83 00:02:55,400 --> 00:02:56,950 This is an IP address, 84 84 00:02:56,950 --> 00:02:59,150 a subnet mask, a default gateway, 85 85 00:02:59,150 --> 00:03:01,010 which is usually just the IP of your router, 86 86 00:03:01,010 --> 00:03:03,860 and a server for either DNS or WINS. 87 87 00:03:03,860 --> 00:03:06,540 Now, DNS is the domain name system. 88 88 00:03:06,540 --> 00:03:08,710 DNS is going to be used to convert domain names 89 89 00:03:08,710 --> 00:03:11,680 used by a website to the IP address of it's server 90 90 00:03:11,680 --> 00:03:13,510 so that your computer can connect to it. 91 91 00:03:13,510 --> 00:03:15,980 Now we're going to cover DNS more in its own video, 92 92 00:03:15,980 --> 00:03:17,750 because there's a lot you need to know about it. 93 93 00:03:17,750 --> 00:03:18,730 But for right now, 94 94 00:03:18,730 --> 00:03:20,800 just realize the DNS is essentially 95 95 00:03:20,800 --> 00:03:22,580 the internet's version of a phone book, 96 96 00:03:22,580 --> 00:03:23,590 where we can look up a name 97 97 00:03:23,590 --> 00:03:25,840 and get a number to connect directly to. 98 98 00:03:25,840 --> 00:03:27,740 Now names to numbers and numbers to names, 99 99 00:03:27,740 --> 00:03:29,740 that's what DNS is all about. 100 100 00:03:29,740 --> 00:03:32,470 For example, when you went to diontraining.com, 101 101 00:03:32,470 --> 00:03:34,610 you're going to be using DNS in the background 102 102 00:03:34,610 --> 00:03:37,220 to determine what the IP address is of my server, 103 103 00:03:37,220 --> 00:03:38,150 so you can connect to it 104 104 00:03:38,150 --> 00:03:40,300 and access our web pages or our videos. 105 105 00:03:40,300 --> 00:03:42,100 That is DNS at work. 106 106 00:03:42,100 --> 00:03:43,700 Now WINS, on the other hand, 107 107 00:03:43,700 --> 00:03:46,930 W-I-N-S, is used within a local area network, 108 108 00:03:46,930 --> 00:03:49,760 specifically WINS is used in Windows domains, 109 109 00:03:49,760 --> 00:03:52,640 and it is known as the Windows Internet Name Service. 110 110 00:03:52,640 --> 00:03:54,240 It's used to enable Windows 111 111 00:03:54,240 --> 00:03:57,600 to identify NetBIOS names on a TCP/IP network 112 112 00:03:57,600 --> 00:04:00,630 and convert those NetBIOS names to IP addresses. 113 113 00:04:00,630 --> 00:04:02,750 Basically, WINS is like DNS, 114 114 00:04:02,750 --> 00:04:05,830 but it only works within a Windows domain environment. 115 115 00:04:05,830 --> 00:04:07,740 So if I wanted to connect to my mail server 116 116 00:04:07,740 --> 00:04:09,200 inside a Windows domain, 117 117 00:04:09,200 --> 00:04:11,540 I could type in its IP address, if I knew it, 118 118 00:04:11,540 --> 00:04:13,810 or I could simply type in the name of the server, 119 119 00:04:13,810 --> 00:04:15,080 something like mailbox 120 120 00:04:15,080 --> 00:04:16,690 or whatever I have named it. 121 121 00:04:16,690 --> 00:04:18,770 Now, when it comes time to do the dynamic assignment 122 122 00:04:18,770 --> 00:04:21,550 of the critical addressing information for each client, 123 123 00:04:21,550 --> 00:04:24,030 we can use four different methods to do this. 124 124 00:04:24,030 --> 00:04:27,303 This includes BOOTP, DHCP, APIPA, and ZeroConf. 125 125 00:04:28,460 --> 00:04:30,260 BOOTP is by far the oldest 126 126 00:04:30,260 --> 00:04:32,670 and least used of these four options. 127 127 00:04:32,670 --> 00:04:34,500 BOOTP or the Bootstrap Protocol 128 128 00:04:34,500 --> 00:04:36,820 was originally introduced in 1985 129 129 00:04:36,820 --> 00:04:39,240 for use in disclosed Unix workstations, 130 130 00:04:39,240 --> 00:04:40,620 because it could dynamically assign 131 131 00:04:40,620 --> 00:04:41,880 the IP address information 132 132 00:04:41,880 --> 00:04:43,070 and then allow the workstation 133 133 00:04:43,070 --> 00:04:45,910 to load a copy of their boot image over the network. 134 134 00:04:45,910 --> 00:04:49,510 Now, BOOTP used a static database of IPs and Mac addresses. 135 135 00:04:49,510 --> 00:04:51,810 So essentially whenever a client connected to the network 136 136 00:04:51,810 --> 00:04:53,600 to initiate the BOOTP process, 137 137 00:04:53,600 --> 00:04:56,080 it would find its Mac address inside its database, 138 138 00:04:56,080 --> 00:04:58,270 and then send the proper IP address that matched it 139 139 00:04:58,270 --> 00:05:01,020 back to the requesting client as its assignment. 140 140 00:05:01,020 --> 00:05:02,990 This wasn't as dynamic as we would like. 141 141 00:05:02,990 --> 00:05:06,980 So in 1993, a newer updated protocol known as DHCP 142 142 00:05:06,980 --> 00:05:09,450 was introduced to replace BOOTP. 143 143 00:05:09,450 --> 00:05:12,940 Now DHCP, or the Dynamic Host Configuration Protocol 144 144 00:05:12,940 --> 00:05:14,960 is going to allow the assignment of an IP 145 145 00:05:14,960 --> 00:05:17,940 based on an assigned scope or pool of addresses, 146 146 00:05:17,940 --> 00:05:19,410 as well as it provides the ability 147 147 00:05:19,410 --> 00:05:21,950 for us to configure numerous other options within it. 148 148 00:05:21,950 --> 00:05:24,550 Now, since DHCP allows me to configure my scope, 149 149 00:05:24,550 --> 00:05:26,877 I can actually tell my DHCP server something like, 150 150 00:05:26,877 --> 00:05:29,430 "Hey, I only want you to hand out addresses 151 151 00:05:29,430 --> 00:05:32,750 that are from 192.168.1.100 152 152 00:05:32,750 --> 00:05:36,170 up through 192.168.1.200." 153 153 00:05:36,170 --> 00:05:38,230 And this gives you about 100 clients 154 154 00:05:38,230 --> 00:05:40,260 that can now be automatically assigned. 155 155 00:05:40,260 --> 00:05:42,020 Every time somebody connects to the network, 156 156 00:05:42,020 --> 00:05:45,140 the DHCP is going to send out one of those IPs from that range 157 157 00:05:45,140 --> 00:05:46,950 and assign it for a given period of time 158 158 00:05:46,950 --> 00:05:49,070 known as a lease to a client. 159 159 00:05:49,070 --> 00:05:51,440 Now, each IP can be borrowed for a certain amount of time 160 160 00:05:51,440 --> 00:05:53,880 from this pool, and when that lease expires, 161 161 00:05:53,880 --> 00:05:56,690 the DHCP server is going to pull back that address. 162 162 00:05:56,690 --> 00:05:59,230 Now this doesn't actually cause a problem for us, 163 163 00:05:59,230 --> 00:06:01,217 because your computer at any time can say, 164 164 00:06:01,217 --> 00:06:03,050 "Hey, I'm still using that address. 165 165 00:06:03,050 --> 00:06:04,140 You can't take it." 166 166 00:06:04,140 --> 00:06:06,277 And in that case, the DHCP server would say, 167 167 00:06:06,277 --> 00:06:08,120 "Oh, okay, you can keep it." 168 168 00:06:08,120 --> 00:06:11,590 And reassigns it for another period by renewing its lease. 169 169 00:06:11,590 --> 00:06:13,407 It's just like if you get a book from the library. 170 170 00:06:13,407 --> 00:06:14,980 Say you were halfway through reading it, 171 171 00:06:14,980 --> 00:06:16,290 and it's going to be due tomorrow, 172 172 00:06:16,290 --> 00:06:18,810 you can take it back to the library and recheck it out. 173 173 00:06:18,810 --> 00:06:22,210 It's the same concept with DHCP and dynamic addresses. 174 174 00:06:22,210 --> 00:06:23,910 Now when the lease does expire 175 175 00:06:23,910 --> 00:06:25,620 and it's no longer needed by the client, 176 176 00:06:25,620 --> 00:06:28,230 it's going to be returned back to the scope or that pool, 177 177 00:06:28,230 --> 00:06:30,430 and be ready to be issued to another client. 178 178 00:06:30,430 --> 00:06:32,800 Essentially, each client can borrow that IP 179 179 00:06:32,800 --> 00:06:33,850 during its assignment 180 180 00:06:33,850 --> 00:06:36,050 and then return it whenever it's done with it. 181 181 00:06:36,050 --> 00:06:37,320 Now this IP management 182 182 00:06:37,320 --> 00:06:40,550 is going to be performed by the DHCP server on our behalf. 183 183 00:06:40,550 --> 00:06:42,410 And it's going to use to manage all of these IPs 184 184 00:06:42,410 --> 00:06:44,620 that are being assigned and returned over time. 185 185 00:06:44,620 --> 00:06:46,900 This is great because we don't have to control it ourselves 186 186 00:06:46,900 --> 00:06:48,800 or keep track of it all manually. 187 187 00:06:48,800 --> 00:06:52,170 Instead, we have the ability to go into it at any time 188 188 00:06:52,170 --> 00:06:53,167 and look at the logs and say, 189 189 00:06:53,167 --> 00:06:58,050 "Hey, who was using the IP 192.168.1.132 190 190 00:06:58,050 --> 00:07:00,030 on September 9th at 3:00 PM?" 191 191 00:07:00,030 --> 00:07:01,330 And then we can figure it out 192 192 00:07:01,330 --> 00:07:04,680 using DHCP's IP address management and their logs. 193 193 00:07:04,680 --> 00:07:06,740 And so this gives us all the benefits of figuring out 194 194 00:07:06,740 --> 00:07:07,670 who did what, 195 195 00:07:07,670 --> 00:07:09,870 while still not having to do any of the management 196 196 00:07:09,870 --> 00:07:12,650 and oversight of handing out these IP addresses. 197 197 00:07:12,650 --> 00:07:14,760 Now, another great thing about DHCP 198 198 00:07:14,760 --> 00:07:15,910 is that it gives our clients 199 199 00:07:15,910 --> 00:07:17,210 all of these different variables 200 200 00:07:17,210 --> 00:07:18,640 that they need to communicate. 201 201 00:07:18,640 --> 00:07:21,210 This includes the dynamic IP address that's being assigned 202 202 00:07:21,210 --> 00:07:22,520 as well as the subnet mask, 203 203 00:07:22,520 --> 00:07:24,930 the default gateway and the DNS server, 204 204 00:07:24,930 --> 00:07:26,580 and if you're using a WIN server, 205 205 00:07:26,580 --> 00:07:28,820 you can also send that through DHCP. 206 206 00:07:28,820 --> 00:07:29,870 This can all be done 207 207 00:07:29,870 --> 00:07:32,490 using the DHCP protocol for us automatically, 208 208 00:07:32,490 --> 00:07:35,790 each and every time a new client connects to the network. 209 209 00:07:35,790 --> 00:07:38,700 Yes, I know I've repeated these four configuration options 210 210 00:07:38,700 --> 00:07:40,250 a bunch of times now. 211 211 00:07:40,250 --> 00:07:41,470 And you know what that means? 212 212 00:07:41,470 --> 00:07:44,130 It means this information is really important. 213 213 00:07:44,130 --> 00:07:47,110 So you simply have to know those four configuration items 214 214 00:07:47,110 --> 00:07:49,180 that DHCP provides to your clients 215 215 00:07:49,180 --> 00:07:51,370 and keep them in mind for test day. 216 216 00:07:51,370 --> 00:07:54,150 Remember that the IP address, the subnet mask, 217 217 00:07:54,150 --> 00:07:56,560 the gateway, and the DNS server's IP. 218 218 00:07:56,560 --> 00:07:58,430 The WIN server is an optional component 219 219 00:07:58,430 --> 00:08:00,210 that may or may not be sent. 220 220 00:08:00,210 --> 00:08:02,610 All right, we're going to talk a lot more about DHCP 221 221 00:08:02,610 --> 00:08:04,660 in a separate video, but for now, 222 222 00:08:04,660 --> 00:08:06,180 you need to remember that DHCP 223 223 00:08:06,180 --> 00:08:08,700 is the modern implementation of BOOTP, 224 224 00:08:08,700 --> 00:08:11,230 and it's commonly used in our modern networks 225 225 00:08:11,230 --> 00:08:13,810 to be able to assign automatically the IP address 226 226 00:08:13,810 --> 00:08:15,140 and other required data 227 227 00:08:15,140 --> 00:08:17,470 for a client to communicate on a network. 228 228 00:08:17,470 --> 00:08:20,370 Now, the third way we can do automatic or dynamic addressing 229 229 00:08:20,370 --> 00:08:23,050 is by using APIPA, A-P-I-P-A, 230 230 00:08:23,050 --> 00:08:26,260 or the Automatic Private Internet Protocol Addressing. 231 231 00:08:26,260 --> 00:08:27,770 Basically if for any reason 232 232 00:08:27,770 --> 00:08:30,470 DHCP cannot complete the assignment process 233 233 00:08:30,470 --> 00:08:32,430 or find an address for you to give to the client 234 234 00:08:32,430 --> 00:08:33,670 because you ran out, 235 235 00:08:33,670 --> 00:08:36,200 then APIPA is going to be used instead. 236 236 00:08:36,200 --> 00:08:37,940 This kind of thing can happen if there's a problem 237 237 00:08:37,940 --> 00:08:40,120 where the client can't reach the DHCP server 238 238 00:08:40,120 --> 00:08:43,440 because of networking issues or something else like that. 239 239 00:08:43,440 --> 00:08:44,420 Now in these cases, 240 240 00:08:44,420 --> 00:08:46,820 the client is going to assign itself an APIPA address, 241 241 00:08:46,820 --> 00:08:48,840 which is a self assigned address. 242 242 00:08:48,840 --> 00:08:51,500 Now by default, on a Windows server or workstation, 243 243 00:08:51,500 --> 00:08:54,330 you're going to find that APIPA is selected by default 244 244 00:08:54,330 --> 00:08:56,260 under the TCP/IP properties 245 245 00:08:56,260 --> 00:08:58,470 under the Alternate Configuration tab. 246 246 00:08:58,470 --> 00:09:00,280 Now this allows the Windows machine 247 247 00:09:00,280 --> 00:09:02,370 to assign itself an address randomly 248 248 00:09:02,370 --> 00:09:06,040 from the 169.254 dot something dot something scope, 249 249 00:09:06,040 --> 00:09:08,170 if it can't reach a DHCP server 250 250 00:09:08,170 --> 00:09:09,380 or it can't contact it 251 251 00:09:09,380 --> 00:09:11,610 and finish the negotiation process. 252 252 00:09:11,610 --> 00:09:12,870 Now APIPA is designed 253 253 00:09:12,870 --> 00:09:15,810 to allow for a quick configuration of a local area network 254 254 00:09:15,810 --> 00:09:18,390 without the need of having a DHCP server. 255 255 00:09:18,390 --> 00:09:20,290 For example, if I take 10 clients 256 256 00:09:20,290 --> 00:09:23,180 and I connect them all to a switch without a DHCP server, 257 257 00:09:23,180 --> 00:09:24,810 these 10 clients will default 258 258 00:09:24,810 --> 00:09:27,810 to picking up their own IP address from the APIPA range, 259 259 00:09:27,810 --> 00:09:31,330 which is 169.254 dot something dot something. 260 260 00:09:31,330 --> 00:09:33,460 Again, because it's a class B address, 261 261 00:09:33,460 --> 00:09:34,830 this is perfectly fine, 262 262 00:09:34,830 --> 00:09:37,610 because they're all going to be on the same local area network. 263 263 00:09:37,610 --> 00:09:39,760 So if I wanted to play Doom on this local area network 264 264 00:09:39,760 --> 00:09:41,740 with these 10 machines, that's fine. 265 265 00:09:41,740 --> 00:09:42,740 They'll all find each other, 266 266 00:09:42,740 --> 00:09:45,010 and they'll talk based on their APIPA addresses 267 267 00:09:45,010 --> 00:09:46,750 without any issues at all. 268 268 00:09:46,750 --> 00:09:48,360 Now, the only problem that will occur 269 269 00:09:48,360 --> 00:09:50,310 is that these are private IP addresses. 270 270 00:09:50,310 --> 00:09:53,670 So they can't be routed outside of our local area network. 271 271 00:09:53,670 --> 00:09:55,870 Therefore, if we need to communicate locally, 272 272 00:09:55,870 --> 00:09:57,150 we can do that using a switch, 273 273 00:09:57,150 --> 00:09:58,680 and everything will be fine. 274 274 00:09:58,680 --> 00:10:01,010 But we're not going to be able to reach the internet 275 275 00:10:01,010 --> 00:10:03,860 because we don't have the same network as the router, 276 276 00:10:03,860 --> 00:10:05,900 because the router had a valid IP address, 277 277 00:10:05,900 --> 00:10:07,310 not an APIPA address. 278 278 00:10:07,310 --> 00:10:08,730 And so we don't have a default gateway 279 279 00:10:08,730 --> 00:10:11,520 to get out of this local network we've created. 280 280 00:10:11,520 --> 00:10:13,510 Now, this is the biggest challenge you're going to have 281 281 00:10:13,510 --> 00:10:15,900 when you have an APIPA address assigned to your clients, 282 282 00:10:15,900 --> 00:10:17,160 because they cannot communicate 283 283 00:10:17,160 --> 00:10:18,750 outside the local area network 284 284 00:10:18,750 --> 00:10:21,950 or with other devices that don't have an IP address as well. 285 285 00:10:21,950 --> 00:10:25,050 If you ever have a computer that starts with 169.254 286 286 00:10:25,050 --> 00:10:26,330 dot something dot something, 287 287 00:10:26,330 --> 00:10:27,220 and you can't figure out 288 288 00:10:27,220 --> 00:10:28,900 why it's not connecting to the internet, 289 289 00:10:28,900 --> 00:10:30,580 well, that's your reason. 290 290 00:10:30,580 --> 00:10:31,700 It's an APIPA address, 291 291 00:10:31,700 --> 00:10:34,370 and APIPA addresses can't get out past the router. 292 292 00:10:34,370 --> 00:10:36,380 And so APIPA addresses are not going to allow you 293 293 00:10:36,380 --> 00:10:37,770 to connect to the internet. 294 294 00:10:37,770 --> 00:10:40,450 Our last dynamic method of configuring an IP address 295 295 00:10:40,450 --> 00:10:42,403 is known as ZeroConf or Zero Configuration. 296 296 00:10:43,390 --> 00:10:45,490 Now ZeroConf is a newer technology 297 297 00:10:45,490 --> 00:10:46,323 that was based on APIPA 298 298 00:10:46,323 --> 00:10:49,380 and can provide you with a lot of the same features as APIPA 299 299 00:10:49,380 --> 00:10:50,800 as well as some new ones. 300 300 00:10:50,800 --> 00:10:53,160 For example, ZeroConf can actually assign 301 301 00:10:53,160 --> 00:10:55,840 an IPv4 link-local address to a client. 302 302 00:10:55,840 --> 00:10:58,070 This is a form of a non writeable IP 303 303 00:10:58,070 --> 00:11:01,040 that's used on a local sub-net, just like APIPA, 304 304 00:11:01,040 --> 00:11:03,540 but the big difference is that with ZeroConf, 305 305 00:11:03,540 --> 00:11:04,970 this client can now have the ability 306 306 00:11:04,970 --> 00:11:07,410 to resolve computer names to IP addresses 307 307 00:11:07,410 --> 00:11:09,280 without the need of DNS, 308 308 00:11:09,280 --> 00:11:11,230 by using something known as mDNS 309 309 00:11:11,230 --> 00:11:13,750 or multicast domain name service. 310 310 00:11:13,750 --> 00:11:17,310 Also ZeroConf can perform a service discovery on a network, 311 311 00:11:17,310 --> 00:11:18,900 so it can find out what things are connected 312 312 00:11:18,900 --> 00:11:20,100 and available for use. 313 313 00:11:20,100 --> 00:11:22,990 So if there's a printer, a scanner, or show file system, 314 314 00:11:22,990 --> 00:11:25,760 you can actually find that using ZeroConf. 315 315 00:11:25,760 --> 00:11:28,300 There've been lots of different implementations of ZeroConf 316 316 00:11:28,300 --> 00:11:29,380 in recent years, 317 317 00:11:29,380 --> 00:11:30,690 and it's called different things 318 318 00:11:30,690 --> 00:11:31,930 depending on the implementation 319 319 00:11:31,930 --> 00:11:33,540 and the product line you're using. 320 320 00:11:33,540 --> 00:11:35,270 For example, on Apple products, 321 321 00:11:35,270 --> 00:11:37,690 ZeroConf is actually called Bonjour, 322 322 00:11:37,690 --> 00:11:40,290 and it's used mostly for service discovery of other clients 323 323 00:11:40,290 --> 00:11:42,470 end devices on the local area network. 324 324 00:11:42,470 --> 00:11:43,780 In Microsoft Windows, 325 325 00:11:43,780 --> 00:11:46,290 they like to call it LLMNR, 326 326 00:11:46,290 --> 00:11:48,770 Link-Local Multicast Name Resolution. 327 327 00:11:48,770 --> 00:11:51,500 And it's going to rely on it as an extension of APIPA 328 328 00:11:51,500 --> 00:11:53,840 to provide for name resolution and service discovery, 329 329 00:11:53,840 --> 00:11:56,270 in addition to providing network conductivity. 330 330 00:11:56,270 --> 00:11:57,360 Now if you're using Linux, 331 331 00:11:57,360 --> 00:12:00,350 ZeroConf is usually implemented using SystemD 332 332 00:12:00,350 --> 00:12:02,110 or the System Daemon Service, 333 333 00:12:02,110 --> 00:12:05,860 specifically the systemd-resolved background service. 334 334 00:12:05,860 --> 00:12:08,350 So remember, there are lots of different ways 335 335 00:12:08,350 --> 00:12:09,880 to assign IP addresses. 336 336 00:12:09,880 --> 00:12:12,270 You can do it manually known as a static assignment 337 337 00:12:12,270 --> 00:12:15,520 or automatically known as a dynamic assignment. 338 338 00:12:15,520 --> 00:12:17,220 If you're using a dynamic assignment, 339 339 00:12:17,220 --> 00:12:19,000 you can do this with one of four methods: 340 340 00:12:19,000 --> 00:12:22,720 BOOTP, DHCP, APIPA, or ZeroConf. 341 341 00:12:22,720 --> 00:12:25,280 Really, it all depends on the needs of your clients 342 342 00:12:25,280 --> 00:12:26,253 and your network.