1 00:00:02,670 --> 00:00:06,810 In this lecture, we'll see the many steps of named resolution. 2 00:00:07,620 --> 00:00:14,670 So in this lecture, we will learn about name resolution process and how Deana's converts names to IP 3 00:00:14,670 --> 00:00:16,090 addresses and vice versa. 4 00:00:16,830 --> 00:00:18,090 What is name resolution? 5 00:00:18,720 --> 00:00:24,680 Name resolution is a matter of converting an IP address to a user friendly computer name. 6 00:00:25,200 --> 00:00:32,430 For example, if you want to connect to Microsoft dot com, you enter Microsoft dot com in the United 7 00:00:32,640 --> 00:00:34,260 and not the IP address. 8 00:00:35,100 --> 00:00:42,600 The process that goes behind directing the Microsoft dot com to its IP address is known as name resolution. 9 00:00:43,230 --> 00:00:48,690 Hostname resolution is defined as translating a hostname to an IP address. 10 00:00:49,110 --> 00:00:57,510 The entire hostname can be no longer than 255 characters and must be alphanumeric, including hyphens 11 00:00:57,510 --> 00:00:58,410 and periods. 12 00:00:58,830 --> 00:01:05,390 But periods can only be used between labels and at the end of a fully qualified domain name. 13 00:01:05,580 --> 00:01:07,350 That is f the end. 14 00:01:08,010 --> 00:01:09,540 What is fqdn? 15 00:01:12,020 --> 00:01:19,250 F Q. The N is a name we have seen so far as fully qualified domain names, they are sometimes written 16 00:01:19,250 --> 00:01:24,560 more formally the training period, for example, Amitay Dot Edu Dot. 17 00:01:25,190 --> 00:01:28,190 This training period indicates that the name is complete. 18 00:01:28,520 --> 00:01:34,010 No additional information should be added to the name when the performing Unnim resolution. 19 00:01:35,220 --> 00:01:41,600 And opposite to this, it is unqualified on unqualified domain name, which is used in combination, 20 00:01:41,620 --> 00:01:46,650 the default to mean a domain search list set the system configuration. 21 00:01:47,280 --> 00:01:48,810 What is DNS space? 22 00:01:49,380 --> 00:01:54,090 The DNS namespace is the set of all names used with d'Eon. 23 00:01:54,360 --> 00:01:59,580 As this space is partitioned hierarchically and in case sensitive. 24 00:02:00,480 --> 00:02:05,820 The current DNS namespace is a three of domains with an unnamed route at the top. 25 00:02:06,720 --> 00:02:10,870 The top echelons of the tree are the so-called top level domains. 26 00:02:10,920 --> 00:02:18,960 That is the LDA, which include generic top level domains, country code, top level domains, internationalized 27 00:02:18,960 --> 00:02:26,070 country code, top level domains and a special infrastructure top level domain called for historical 28 00:02:26,070 --> 00:02:27,260 reasons, ARTPOP. 29 00:02:28,050 --> 00:02:33,090 So let us now see how aname resolution process occurs in the image. 30 00:02:33,270 --> 00:02:34,260 You can see that. 31 00:02:34,500 --> 00:02:40,080 Let us say suppose you type w w w dot abc dot com in your browser. 32 00:02:40,530 --> 00:02:47,100 Now your browser doesn't know what ABC dot com means because a browser redirects only when it has been 33 00:02:47,100 --> 00:02:48,600 directed to an IP address. 34 00:02:49,020 --> 00:02:55,530 So browser passes that request to resolve your resolver is nothing but an Internet service provider. 35 00:02:55,920 --> 00:02:59,610 Internet service provider has the ISP table and its cache. 36 00:03:00,270 --> 00:03:07,950 So the ISP table cache is a table which consists of the website name alongside its IP address. 37 00:03:08,580 --> 00:03:16,580 Let us consider the case with the resolver does not find IP address for w w w dot a C dot com. 38 00:03:17,220 --> 00:03:21,830 So the resolver passes the query to the DNS local server. 39 00:03:22,710 --> 00:03:27,930 Now the DNS local server passes the query to the router DNS server. 40 00:03:28,440 --> 00:03:31,710 In our case the root server is dot com. 41 00:03:32,550 --> 00:03:41,160 So the root server replies that, OK, this is a dot com and please check in the DNS dot com top level 42 00:03:41,160 --> 00:03:41,700 domains. 43 00:03:42,150 --> 00:03:51,840 So the DNS root server replies back to the DNS local server saying that please check the domain in dot 44 00:03:51,840 --> 00:03:53,700 com top level domain list. 45 00:03:54,510 --> 00:04:02,370 DNS logos is OK and DNS Local again puts a query to DNS dot com top level domain. 46 00:04:03,060 --> 00:04:11,430 Now DNS dot dot com top level domain gives an answer and says, okay, this is A.B.C., so please check 47 00:04:11,430 --> 00:04:13,860 in the ABC dot com namespace. 48 00:04:14,490 --> 00:04:24,840 So DNS Local again puts a query to domain name servers, ABC dot com space and finally ABC dot com replies 49 00:04:24,840 --> 00:04:33,750 with the IP address and now DNS Local also update the IP address in its own table and forwards that 50 00:04:33,750 --> 00:04:40,890 IP address to the resolver resolver to put that IP address into its stable and finally it. 51 00:04:41,940 --> 00:04:44,230 And so that IP address to your browser. 52 00:04:44,670 --> 00:04:52,020 Now all this process happens in a fraction of seconds and this process is known as the name resolution 53 00:04:52,020 --> 00:04:52,590 process. 54 00:04:55,080 --> 00:05:01,530 Let us have a quick recap, so we saw what is named resolution, we saw what our top level domains, 55 00:05:01,770 --> 00:05:05,170 what are authority domains and what are lower level domains. 56 00:05:05,730 --> 00:05:10,710 We also saw about the named resolution process and the dayanim namespace. 57 00:05:12,420 --> 00:05:19,140 In the next lecture, we will see which protocols do we use for establishing connection with the name 58 00:05:19,140 --> 00:05:19,530 server. 59 00:05:20,340 --> 00:05:22,960 Now, you must have got the question, why do we need. 60 00:05:23,280 --> 00:05:25,290 Why do we need to use a protocol? 61 00:05:26,150 --> 00:05:29,330 OK, so this answer will be answered in the next lecture.