DNS Zones

but now you should have a pretty good grasp of things like domains and subdomains in fact if you look at a picture like this you should be able to see things like the X Y Z domain which is inside of calm which is underneath the the root domain but to really understand DNS you have to learn about zones and delegations and they're a little bit different than domains and I want to show you zones and delegations with this picture here but not not quite yet we're going to show you something a little more familiar which looks kind of like an organization chart for this company so let's kind of look and see what we got here first what we've got is this company called XYZ it's divided up into three divisions the Human Resources Division engineering and marketing and marketing is pretty small just got a couple of people working for it HR is a little bit bigger so it is subdivided into payroll and personnel each one of which has a couple people in it and then engineering is the biggest division of all it's divided up into development and testing testing as one person in it but development is broken up into the web and mobile divisions or departments each of which has a couple people in it now so this company is headed up by CEO or president let's say his name is Steve and HR is headed up by Phil engineering is Stacy and marketing is Chris so we can kind of say that that Steve runs the entire company but has delegated responsibilities for various divisions off to other people here for example Chris here runs the marketing department now because this is a relatively small department Chris says I'm just going to run the whole thing myself same thing with Phil Steve has delegated off the responsibility for Human Resources off to Phil so this is Phil's area and then finally engineering belongs to Stacy now Stacy can't run this entire thing and so what what Stacy's decided to do is find a manager to run development let's say this is Stan and so stan has his own little area here and then the rest of it belongs to Stacy so I'll get to what this circle here looks like in just a moment here so what each one of these division directors has done is is they're going to make kind of like a phone directory for each one of their divisions there so so Chris is going to make one here it's going to write down that this is the marketing phone directory and we're going to put two people in there Bob let's say Bob is that extension 20 and Frank is at extension 22 and Phil is going to do the same thing so this is the HR phone directory and but but we got a little more complicated thing going on here because Jan works in payroll we're going to have to list a Department of Jan works for as well so Jan who's in payroll let's say the she's at extension 32 here's B she also works in payroll maybe she's at extension 33 and then Frank here which is a different Frank from this one over here that's why we're writing down what department they work in personnel and maybe Frank is that extension 41 and then Stan does a similar thing he makes his list let's see this is the development phone list and here's Dan who works in web maybe he is that extension 53 and then there's Sue who works in the web development maybe she's at 57 and then Sam in the mobile area is maybe at 58 and then what's what's Stacy going to do here let's see this is the engineering phone list so Stacy's got Dan working directly for her this is a really small department here so Stacy says I'm just going to be the manager for Dan so we're going to write down Dan it was in testing maybe he's at extension 18 and then but but because development is run by Stan Stacy says I don't really care what Stan does you know Stan's made his own phone list here so I'm just going to write down that development as a whole is maybe at extension five so we've got these circles drawn here we've got these phone lists here and I think we now we're ready to draw the circle around Stacy Stacy's area you know obviously includes Dan and testing but also includes just the top part of Stan's area and so what this is saying is that that Stacy knows about Dan and the testing but all Stacy needs to know about development is that it's run by Stan you know let's say a phone call comes in up here at the top phone call comes in and Steve or Steve's assistant picks it up and let's say the person is calling for Frank over here in personnel so what's these going to do is going to say oh well they're asking for someone in personnel I know personnel is part of HR so I'm just going to hand off the call to fill and then Phil is going to consult his list here and say okay looking for Frank there in personnel extension 41 so they're going to direct the call to extension 41 and this call is handled let's say another call comes in and this person is looking for Sam over here in Mobile so Steve says okay well not only they're looking for Stan in mobile but they know that that the caller knows that that Sam works in the development and also development than engineering so Steve receives us call and says okay looking for Sam and mobile development engineering I know that engineering is handled by Stacy so I'm just going to hand off to called Stacy Stacy looks in her book which is over here and says well I don't know Sam's number but I know the developments that extension five so I'll just hand off the call to extension five which comes over here to stand Stan looks in his list here and says ah I know what Sam is Sam and works in the mobile he's at extension 58 so that's kind of like how how calls get routed through this company is each one of the people that has one of these lists looks on it to see where the call should be handed off so this is kind of begs an important question here is what list is Steve looking at so actually Steve's got his own list which I'm going to squeeze in somewhere over here let's so you put it over here so this is for XYZ company and it says that HR is handled by Phil and let's say HR is that extension to engineering is that extension 3 and marketing is that extension for all right so so there's Steve's phone list so again let's say calls coming in for Dan Steve receives the call the caller says I'm looking for Dan and testing in the engineering division so Steve says well I don't know Dan's number but I'll hand you off to extension 3 so the call comes in to Stacy Stacy looks at her list and goes where's that that's over here ah says that I know I know where Dan is Dan is in testing is in extension 18 so there you go and then it connects to call in to Dan directly so here's where all these terms come in you can probably guess what this is already but each one of these circles here is a zone so there's the marketing zone there's the HR zone the development zone and the engineering zone and finally there's there's the big one here at the top which is the X Y Z zone so we can say kind of like the each zone is an organizational area of a domain so it's not necessarily an individual domain you can see that they kind of overlapped and they have kind of an odd shape here and sometimes zones can be kind of deep and sometimes they're rather shallow so it just depends upon who wants to take responsibility for routing information through these domains to their ultimate destination so each one of these zones has information about it and each one of these zones also is particularly if there's one below it has information about how to get to the one thing below it and so like here's Stan's example here there's only States he only needs to know how to get a call to the top of the development how to get a call to stand and then Stan takes over from there and routes the call down to its ultimate destination so I guess you can kind of say like you know a zone is a thing an organizational thing and a delegation is an action each one of these zones has just a little bit of information in it but they get connected together through connections like this one right here that says to get from engineering to development just call extension five and whoever answers will be able to throughout the call directly okay so so now I'm kind of done with this picture here let's go back and look at that first picture that was at the start of the video so this is essentially the same picture but it's just drawn in in domain format so you can probably already see some of the things here if you know right here is where the top of the XYZ domain starts but it's also where the top of the XYZ zone starts and there's a zone right here there is a zone here around development there is a zone realm marketing little tiny one and then Engineering's got one but it overlaps the the top of development just just buy one just enough to be able to connect in the two together and then XYZ itself the entire company is a zone and so so where does that go so that basically everything that is at that top level underneath XYZ is a zone the comm domain which is also a zone by itself delegates off responsibility for the X Y Z domain off of two to two I think it was Steve and then Steve delegates Human Resources off to fill it delegates off engineering to Stacey delegates off marketing to Chris and then these these little stragglers here like www and mail those just get handled by Steve Steve you know if a call comes in and says I need to talk to the web server see if it's all I know where that is it's just right here but again you know if somebody wants to talk to someone over here and the the web department then Steve has to hand it off of Stacey Stacey hands it off to stand and stand directs it off to where it's supposed to go so I hope this video kind of clarified what the tone and a delegation is and and how they differ from domains and like I saw set at the beginning the video there's domains all over the place here basically every single one of these words in this picture is a domain but the zones can be larger pieces so so as we go through all these videos you're going to see how zones and delegations and domains kind of all relate to each other and then when we start putting together the databases and the files to make an actual DNS domain the zones of delegations will come back and you'll see those terms again you

Channel: Barry Brown

Views: 92,264

Keywords: dns, computer science

Id: dk7GS6GbeiY

Length: 13min 9sec (789 seconds)

Published: Sun Jun 24 2012