1 00:00:00,060 --> 00:00:00,893 In this video, 2 00:00:00,893 --> 00:00:03,030 we're going to discuss IP settings. 3 00:00:03,030 --> 00:00:05,790 This can occur when you have the incorrect IP address, 4 00:00:05,790 --> 00:00:09,120 subnet mask, gateway, or DNS server IP address 5 00:00:09,120 --> 00:00:10,200 assigned to a client, 6 00:00:10,200 --> 00:00:12,960 and it'll cause issues for you with your IP settings. 7 00:00:12,960 --> 00:00:14,970 Remember the fact that every network client 8 00:00:14,970 --> 00:00:17,040 needs four key pieces of information 9 00:00:17,040 --> 00:00:19,230 in order to communicate properly on the network. 10 00:00:19,230 --> 00:00:21,720 This is their IP address, their subnet mask, 11 00:00:21,720 --> 00:00:23,340 the IP of their default gateway, 12 00:00:23,340 --> 00:00:25,350 and the IP of their DNS server. 13 00:00:25,350 --> 00:00:27,330 Now let's take a look at a static assignment 14 00:00:27,330 --> 00:00:29,040 on this OS X client. 15 00:00:29,040 --> 00:00:32,009 Notice here we have three key pieces of information shown, 16 00:00:32,009 --> 00:00:33,960 the IP address, the subnet mask, 17 00:00:33,960 --> 00:00:36,060 and the router or default gateway. 18 00:00:36,060 --> 00:00:38,280 The DNS server IP is on a different tab 19 00:00:38,280 --> 00:00:40,080 and it really doesn't matter for this example 20 00:00:40,080 --> 00:00:42,660 as long as we don't need to conduct name resolutions. 21 00:00:42,660 --> 00:00:44,940 So you are called to troubleshoot this client 22 00:00:44,940 --> 00:00:46,770 because they can't access the internet. 23 00:00:46,770 --> 00:00:48,540 Let's assume you already tried to ping the server 24 00:00:48,540 --> 00:00:51,060 at 8.8.8.8, and it failed. 25 00:00:51,060 --> 00:00:54,060 So you know you have some kind of a routing issue here. 26 00:00:54,060 --> 00:00:55,530 What could the problem be? 27 00:00:55,530 --> 00:00:57,660 Now, I want you to go ahead and pause the video here 28 00:00:57,660 --> 00:01:00,150 and look at it and see if you can figure out the issue. 29 00:01:00,150 --> 00:01:01,620 All right, I'm going to count to five. 30 00:01:01,620 --> 00:01:05,700 One, two, three, four, five. 31 00:01:05,700 --> 00:01:06,900 All right, you're back. 32 00:01:06,900 --> 00:01:08,460 Did you figure out the issue? 33 00:01:08,460 --> 00:01:09,293 In this case, 34 00:01:09,293 --> 00:01:11,910 the issue is that we have the wrong default gateway. 35 00:01:11,910 --> 00:01:16,590 Notice the IP address is 192.168.1.200 36 00:01:16,590 --> 00:01:21,450 and it has a subnet mask of 255.255.255.0. 37 00:01:21,450 --> 00:01:22,830 With this subnet mask, 38 00:01:22,830 --> 00:01:24,930 the default gateway would have to be an IP 39 00:01:24,930 --> 00:01:28,470 of 192.168.1. something 40 00:01:28,470 --> 00:01:33,120 because it's in this 192.168.1.0/24 network 41 00:01:33,120 --> 00:01:34,710 for us to be able to reach it. 42 00:01:34,710 --> 00:01:38,160 Now, if the default gateway is set at 10.0.1.1, 43 00:01:38,160 --> 00:01:40,320 and this is truly the IP of my router, 44 00:01:40,320 --> 00:01:42,120 then I have an incorrect IP address 45 00:01:42,120 --> 00:01:47,040 because again my subnet mask of 255.255.255.0 46 00:01:47,040 --> 00:01:50,970 if applied to the router's IP address of 10.0.1.1 47 00:01:50,970 --> 00:01:52,890 would tell me I need to have something in the network 48 00:01:52,890 --> 00:01:56,310 of 10.0.1.0/24. 49 00:01:56,310 --> 00:01:58,620 So to get this client to connect to the internet 50 00:01:58,620 --> 00:02:00,450 and have its traffic properly routed, 51 00:02:00,450 --> 00:02:05,450 I need to change either the default gateway to 192.168.1.1 52 00:02:05,670 --> 00:02:10,139 or change the IP address to 10.0.1.200 53 00:02:10,139 --> 00:02:11,490 or something like that. 54 00:02:11,490 --> 00:02:13,680 All right, let's take a look at another example. 55 00:02:13,680 --> 00:02:15,540 This one comes from a Windows client. 56 00:02:15,540 --> 00:02:16,860 Just like our last example, 57 00:02:16,860 --> 00:02:20,460 this client cannot ping 8.8.8.8 successfully. 58 00:02:20,460 --> 00:02:22,740 So you see the client has a statically assigned 59 00:02:22,740 --> 00:02:27,000 IP address of 192.168.1.200. 60 00:02:27,000 --> 00:02:31,800 Its subnet mask is 255.255.255.128. 61 00:02:31,800 --> 00:02:36,390 And the default gateway here is 192.168.1.1. 62 00:02:36,390 --> 00:02:38,220 All right, go ahead and pause the video. 63 00:02:38,220 --> 00:02:40,140 I want to see if you can identify the issue 64 00:02:40,140 --> 00:02:41,610 and think about how you're going to fix 65 00:02:41,610 --> 00:02:43,860 this client's network connectivity issues. 66 00:02:43,860 --> 00:02:45,210 Pause the video and come back 67 00:02:45,210 --> 00:02:49,740 in one, two, three, four, five. 68 00:02:49,740 --> 00:02:52,380 All right, you're back. Did you figure this one out? 69 00:02:52,380 --> 00:02:54,660 Let's take a closer look at that subnet mask. 70 00:02:54,660 --> 00:02:58,620 Notice it wasn't a classful Class C of 255.255.255.0. 71 00:03:00,630 --> 00:03:05,630 So this isn't the 192.168.1.0/24 network 72 00:03:06,450 --> 00:03:09,900 and it doesn't have 254 usable IP addresses. 73 00:03:09,900 --> 00:03:13,697 Instead, we have a subnet mask of 255.255.255.128. 74 00:03:16,380 --> 00:03:20,430 This gives us a /25 network using CIDR notation. 75 00:03:20,430 --> 00:03:24,360 That means we only have 126 usable IP addresses. 76 00:03:24,360 --> 00:03:28,950 So if our gateway is 192.168.1.1 77 00:03:28,950 --> 00:03:33,750 and we have a subnet mask of 255.255.255.128 78 00:03:33,750 --> 00:03:38,550 then our network IP is 192.168.1.0 79 00:03:38,550 --> 00:03:43,550 and our broadcast is going to be 192.168.1.127. 80 00:03:44,070 --> 00:03:46,080 Everything between those two ranges 81 00:03:46,080 --> 00:03:48,150 is going to be usable IPs, 82 00:03:48,150 --> 00:03:53,010 but our client was assigned 192.168.1.200 83 00:03:53,010 --> 00:03:55,290 and that means it's assigned into a range 84 00:03:55,290 --> 00:03:56,850 that's in another network, 85 00:03:56,850 --> 00:03:59,940 so that IP address and gateway aren't on the same subnet. 86 00:03:59,940 --> 00:04:01,950 This would explain why we can't route our traffic 87 00:04:01,950 --> 00:04:05,160 to the network because we can't reach our default gateway. 88 00:04:05,160 --> 00:04:06,900 This is going to be a problem for us. 89 00:04:06,900 --> 00:04:10,020 So our solution would be to change our IP address 90 00:04:10,020 --> 00:04:13,050 to something on the same subnet as that default gateway, 91 00:04:13,050 --> 00:04:16,589 like 192.168.1.100, 92 00:04:16,589 --> 00:04:18,120 or we could see if there's a gateway 93 00:04:18,120 --> 00:04:19,829 on the same subnet as our client. 94 00:04:19,829 --> 00:04:21,930 This means we need a gateway with an IP address 95 00:04:21,930 --> 00:04:26,670 of 192.168.1.129 or something between there 96 00:04:26,670 --> 00:04:30,000 and 192.168.1.254 97 00:04:30,000 --> 00:04:34,710 because our network IP will be 192.168.1.128 98 00:04:34,710 --> 00:04:39,150 and the broadcast will be 192.168.1.255 99 00:04:39,150 --> 00:04:42,240 if we're using the subnet mask for a /25 network 100 00:04:42,240 --> 00:04:46,080 of 255.255.255.128. 101 00:04:46,080 --> 00:04:46,913 All right. 102 00:04:46,913 --> 00:04:48,210 Now if you're going to connect to a website 103 00:04:48,210 --> 00:04:50,370 by its domain name and that isn't working, 104 00:04:50,370 --> 00:04:53,850 we need to look at the DNS IP server configuration. 105 00:04:53,850 --> 00:04:55,290 In this case, you'd want to ensure 106 00:04:55,290 --> 00:04:56,760 you have a working DNS server 107 00:04:56,760 --> 00:04:59,310 and the IP has been properly entered on the client. 108 00:04:59,310 --> 00:05:01,080 If you don't have your own DNS server, 109 00:05:01,080 --> 00:05:04,890 you can always set your DNS server's IP to 8.8.8.8 110 00:05:04,890 --> 00:05:07,620 which is the public DNS server hosted by Google. 111 00:05:07,620 --> 00:05:09,420 So here you can see the DNS server 112 00:05:09,420 --> 00:05:13,530 is set to 192.168.1.1 as the primary 113 00:05:13,530 --> 00:05:17,100 and 192.168.1.2 as the secondary. 114 00:05:17,100 --> 00:05:19,530 This is fine as long as the DNS servers there 115 00:05:19,530 --> 00:05:21,540 are running on those IP addresses. 116 00:05:21,540 --> 00:05:23,430 Now, if you don't have DNS servers, 117 00:05:23,430 --> 00:05:26,100 then you want to reconfigure those to the public DNS servers 118 00:05:26,100 --> 00:05:29,640 at 8.8.8.8 and 8.8.4.4. 119 00:05:29,640 --> 00:05:31,773 Both of those are Google's DNS servers.