1 1 00:00:00,800 --> 00:00:02,270 Network services. 2 2 00:00:02,270 --> 00:00:03,570 In this section of the course, 3 3 00:00:03,570 --> 00:00:05,740 we're going to discuss some network services 4 4 00:00:05,740 --> 00:00:08,750 that are testable on the CompTIA Network+ exam. 5 5 00:00:08,750 --> 00:00:11,310 For the exam, you must be able to explain the purpose 6 6 00:00:11,310 --> 00:00:13,610 of each network service, it's use, 7 7 00:00:13,610 --> 00:00:16,800 and some basic configuration information for each one. 8 8 00:00:16,800 --> 00:00:21,260 Specifically, we're going to talk about DHCP, DNS, and NTP 9 9 00:00:21,260 --> 00:00:23,070 in this section of the course. 10 10 00:00:23,070 --> 00:00:26,770 Now, DHCP is the Dynamic Host Configuration Protocol. 11 11 00:00:26,770 --> 00:00:29,210 DHCP is a network management protocol 12 12 00:00:29,210 --> 00:00:31,340 that is used for internet protocol networks 13 13 00:00:31,340 --> 00:00:34,580 for the automatic assignment of IP addresses to devices, 14 14 00:00:34,580 --> 00:00:37,600 as well as to providing the subnet mask, default gateway, 15 15 00:00:37,600 --> 00:00:40,100 and DNS server for the device to use 16 16 00:00:40,100 --> 00:00:41,810 when it connects to the internet. 17 17 00:00:41,810 --> 00:00:43,650 We're going to talk more about DHCP 18 18 00:00:43,650 --> 00:00:46,370 and its configuration options in a separate video 19 19 00:00:46,370 --> 00:00:49,020 to more fully cover DHCP in depth. 20 20 00:00:49,020 --> 00:00:52,920 DHCP is going to operate over ports 67 and 68 21 21 00:00:52,920 --> 00:00:56,490 using the User Datagram Protocol, known as UDP. 22 22 00:00:56,490 --> 00:01:00,610 Next we have DNS, which is the Domain Name System. 23 23 00:01:00,610 --> 00:01:03,610 DNS is a protocol that's used to convert domain names 24 24 00:01:03,610 --> 00:01:05,770 to IP addresses using a hierarchal 25 25 00:01:05,770 --> 00:01:08,020 and decentralized system of naming. 26 26 00:01:08,020 --> 00:01:10,750 DNS is a phone book for the internet, essentially. 27 27 00:01:10,750 --> 00:01:14,070 So, when you type in diontraining.com into your web browser, 28 28 00:01:14,070 --> 00:01:17,350 you don't have to memorize the IP address of my web server. 29 29 00:01:17,350 --> 00:01:20,340 Instead, DNS is going to convert it for you. 30 30 00:01:20,340 --> 00:01:22,900 DNS is a bit unique in that it operates both 31 31 00:01:22,900 --> 00:01:26,970 over UDP and TCP using the exact same port, 32 32 00:01:26,970 --> 00:01:28,530 port 53. 33 33 00:01:28,530 --> 00:01:31,940 When DNS is conducting a domain name query or lookup, 34 34 00:01:31,940 --> 00:01:35,320 it's going to use UDP to accept that request from a client 35 35 00:01:35,320 --> 00:01:38,120 and then send the response from that server back. 36 36 00:01:38,120 --> 00:01:41,200 But, if DNS is going to be doing a zone transfer 37 37 00:01:41,200 --> 00:01:42,790 between two different servers, 38 38 00:01:42,790 --> 00:01:44,950 it's going to use TCP for that. 39 39 00:01:44,950 --> 00:01:48,270 Now, a zone transfer is the method used by DNS servers 40 40 00:01:48,270 --> 00:01:50,400 to share information between themselves 41 41 00:01:50,400 --> 00:01:52,220 about which domains they have 42 42 00:01:52,220 --> 00:01:55,360 and the associate IP addresses for those domains. 43 43 00:01:55,360 --> 00:01:57,510 For this server-to-server communication, 44 44 00:01:57,510 --> 00:02:00,040 TCP is going to be used instead of UDP 45 45 00:02:00,040 --> 00:02:01,710 because these servers want to verify 46 46 00:02:01,710 --> 00:02:04,280 that the information was received by the other server 47 47 00:02:04,280 --> 00:02:07,420 and that it was properly received during that transfer. 48 48 00:02:07,420 --> 00:02:10,770 Again, we're going to talk more about DNS in a separate video, 49 49 00:02:10,770 --> 00:02:12,250 where we could spend more time digging 50 50 00:02:12,250 --> 00:02:15,860 into all the different DNS record types and their uses. 51 51 00:02:15,860 --> 00:02:18,400 Finally, we're going to talk about NTP 52 52 00:02:18,400 --> 00:02:20,490 or the Network Time Protocol. 53 53 00:02:20,490 --> 00:02:22,570 NTP is a networking protocol 54 54 00:02:22,570 --> 00:02:24,520 that's used for the synchronization of clocks 55 55 00:02:24,520 --> 00:02:26,350 between different computer systems 56 56 00:02:26,350 --> 00:02:28,460 that communicate over a packet-switched, 57 57 00:02:28,460 --> 00:02:30,650 variable-latency data network. 58 58 00:02:30,650 --> 00:02:34,250 Now, TCP IP networks are packet-switched networks. 59 59 00:02:34,250 --> 00:02:38,030 So, NTP is going to be used for the synchronization of time 60 60 00:02:38,030 --> 00:02:42,160 across our IP-connected servers when using TCP. 61 61 00:02:42,160 --> 00:02:45,120 NTP is kind of special because it's really old 62 62 00:02:45,120 --> 00:02:47,210 and yet, we still use it today. 63 63 00:02:47,210 --> 00:02:50,500 In fact, NTP is one of the oldest internet protocols 64 64 00:02:50,500 --> 00:02:52,780 that we still use in modern networks. 65 65 00:02:52,780 --> 00:02:57,780 NTP data is going to be sent using UDP over port 123. 66 66 00:02:57,780 --> 00:03:00,320 We're going to be spending an entire video in this section 67 67 00:03:00,320 --> 00:03:02,470 talking all about NTP as well, 68 68 00:03:02,470 --> 00:03:04,500 so you can better understand how it operates, 69 69 00:03:04,500 --> 00:03:06,810 both from the client and server perspective 70 70 00:03:06,810 --> 00:03:09,560 to make sure everyone's using the same time in, 71 71 00:03:09,560 --> 00:03:12,420 so you can understand why time is so important. 72 72 00:03:12,420 --> 00:03:14,050 So, in this section, 73 73 00:03:14,050 --> 00:03:16,480 we're going to be diving into domain one, 74 74 00:03:16,480 --> 00:03:18,050 networking fundamentals, 75 75 00:03:18,050 --> 00:03:20,620 and we're going to focus only on one objective here. 76 76 00:03:20,620 --> 00:03:21,453 Objective 1.6. 77 77 00:03:22,710 --> 00:03:23,920 This objective states 78 78 00:03:23,920 --> 00:03:25,810 that you have to be able to explain the use 79 79 00:03:25,810 --> 00:03:28,350 and purpose of network services. 80 80 00:03:28,350 --> 00:03:30,040 All right, let's get started talking 81 81 00:03:30,040 --> 00:03:34,483 all about DHCP, DNS, and NTP in this section of the course.