Time
3 hours 28 minutes
Difficulty
Intermediate
CEU/CPE
4

Video Description

Networks, Servers, Databases - OH MY! This session offers an introductory look into Domain Naming System (DNS) and offers a look into the history of DNS. Participants learn about: - NetBIOS servers - TCP/IP servers Dimensions are also discussed in this session; 1-dimensional servers and 3-dimensional servers, as well as states; dynamic and static.

Video Transcription

00:04
I Siberians, this is Kelly Hander Hand once again and I would like to walk us through in the next of the multi part series on introduction and exploration of DNF. I fully believe that D N s is the root of all good and evil on a network.
00:20
And when things were configured right and everything's humming along life is good
00:24
But when we start, have issues and problems with the N s with resolution with records not being created are located. That's when we really start to see problems. So what I want to do in the next series of cyber E sessions
00:38
is I want to start out of beginning. Let's talk about the basics of D. N s why it was created, how it's more throughout the years
00:45
and then look at as we move to the more advanced concepts house owns air created, what are the information's in? What's the information in those owns and then how things like zone transfer sporting delegation, All that stuff works. So today we're gonna focus on the history and just an introduction to D. N s.
01:04
Okay,
01:06
so we start out with the n s, you know, just a zone introductory level. Dina stands for domain naming system right domain naming system, and the idea is, we like names I could not tell you if my life depended on it. The i p address for weather dot com
01:23
Right, But I can figure out where to go by name if I want to know if it's raining or not.
01:26
So what we need is we need just like a telephone book. I can't remember anybody's phone number, but I know their name. And as long as I have somewhere to look it up, I'm good.
01:36
All right. So let's talk about name resolution for a little bit because it's really changed throughout the years and from very early on, we know Hey, people like names they don't like I p addresses. They certainly don't like buying area or hex decimal addresses. Let's let him use names
01:53
now. There were really kind of two schools of thought on what type of names
01:57
we're gonna let people use. We look at
02:00
on really two distinct camps.
02:04
The first camp,
02:06
these guys were in the Net bios camp
02:07
and the Net buyers, Camp said. Let's keep it simple.
02:13
This Internet thing will never catch on. All people are gonna want to do is connect the servers and systems within their own building. Right. So we're gonna have a one dimensional name. So that's a quality of net bias. A one dimensional name. And I'll show you what I mean. Annette bios name. Very well. Maybe server one,
02:32
right?
02:32
Nothing too exciting or flashy about that. And if you just stop and think about how many server ones there might be on the planet, that's a pretty overwhelming amount. But the ideas Hey, in my little office of 25 people, there is only one server one. You know what? My second server skull,
02:51
it's her too.
02:53
All right, so that's the Net bios idea. Now, there was another school of thought, which is really kind of the TCP I P camp in the TCP I P camp said
03:04
that this Internet thing is gonna be bigger than it is right now. And so we're gonna do is we're gonna be very forward thinking, and we're gonna prepare, not just for local area network name resolution, but for worldwide name resolution. They said we don't leave one dimensional names. We need the three d name space.
03:22
So instead of Server one,
03:24
we've got server one
03:27
at cyber ery dot com.
03:30
And even though there could be a zillion server ones, there should only be one server one at cyberia dot com. Right. And this name should be reserved two, or should be able to be mapped to only one server on the public. TCP AKI the Internet. Right.
03:47
All right. So how are we gonna make this work?
03:52
Well, one of the first ways that we look to make this work in the TC khaki camp, we had a file called the Hosts file. And we still have that file, so we look to use it less and less.
04:02
All right, so what's the hosts file?
04:05
It's a static past file. Hey, well, right there. We have problems. If it's a static file, that means I, as a network administrator, are going in there and manually updating it. That's no good. Not to mention that, but after I manually updated, I have to push that text file out to all my clients and production.
04:25
And then every time something changes, guess what I get to do again.
04:28
I get to go back and update it. Push it out to everybody in production. A static text file. But what it did was it mapped the f q D in. That's a big word with the N S to an I P address. Okay, what's the F Cody in fully qualified domain name, Fully qualified domain name.
04:47
So what? That means server one at cyber harry dot com.
04:51
That's a fully qualified domain name. Where, as here, we just have ah, that bias name so f duty and is much more thorough in defining the location of the object of the system host. Okay, so now
05:08
the Net bios, folks, and specifically that bias was very big with Windows systems.
05:12
And they said, this host file seems like a good idea. Let's do that.
05:16
But let's call it something totally different. So they don't think we ripped it off?
05:20
I shouldn't say that, but I just
05:24
our Ellen hosts. Paul, would you think that waas It was a static text file mapping that bias names toe I P.
05:33
So early on, when we looked at the static name resolution, you'd have two files on your host system. You would have an l M host while in the hosts file. So applications and many applications, you know back 10 15 years ago used Net bios names. So for net by his name resolution,
05:53
those applications went to the Ellen Post file or were able to pull from the Net bios name, file that Ellen host file
06:00
and find the resolution they needed Say, my deal with the host file.
06:04
The problem with that, though, is like I said, I have to manually update. And then every time I make those updates, I have to push it out. All my hosts and changes can happen very frequently.
06:15
All right? So rather than having a static text file, uh, resolved residing on all my hosts and depending upon that fully for name resolution, what we did is we
06:29
came up with static D. N s. So what was static D. N s? It was a database. Now again, it was static, but it was a database
06:41
of f. Q. Tien's. So what that meant is, rather than having to push this host file out, over and over and over and over again, it's things changed all my host. I would simply tell my hosts where to go for name resolution. And so I would configure the TCP I p properties. Here's the address of my d n A server.
07:00
Every time in f Q T and needed resolution,
07:02
my client would go to D. N s and say, Hey, what's this I p address A for this f udn? The problem, though again static?
07:12
Well, windows got very smart, and they said then this is a pain because it's static. It still requires a network admin to just update and update an update. Because if you've worked with the HCP at all or in network environments, things change all the time.
07:29
I p addresses or leased for a relatively short period of time, they can change.
07:33
Service's come and go. We really want to get away from stat. Okay, so and by the way, a lot of this we're talking about 2000 early two thousands. Okay, so Windows, let's do this.
07:46
Let's come up with Windows Internet naming service, which is a database mapping guessed it that bios to I p addresses. But here was the thing that was cool about wins. It was dynamic. Now, the theory about the dynamic database is
08:07
you start wins
08:07
you allow dynamic updates. A client comes online and it goes and registers a type The address with the wind server. It's automatic. I don't have to go in and copulate that. That doesn't mean work perfectly. But, man, if I was in a Windows 2000 environment and I had to choose between D. N s and wins wins looks
08:26
awfully, awfully good.
08:30
But here's the problems with winds, Windows, Internet naming service. So what that man is who was gonna be able to come up and register themselves with the wind server is gonna be There's Microsoft clients, right? What is a UNIX client or Lennox Kleiner? Any of those other clients know about wins, and the answer is not much, right?
08:50
So even though
08:50
this was a good idea because it was bound to windows that was very limiting. But if you were on a network in the, you know, early two thousands, you had a wind server assuredly Okay, you may still today and we'll talk about why.
09:07
All right, so what's the big change that evolved with V. N s? Well, we went from static to D
09:16
D N s. What do you suppose that new D stands for dynamic D N s And again we're talking about 2003. Give or take, I can't remember who was 4003. That window's implemented dynamic DNF. But what we get here is we get
09:33
support for D. N s, which is part of the TCP I p suite of service is
09:39
so any client can use it as long as it supports T C P I p. We're not bound to Windows,
09:45
and it's now dynamics who A client can come on line and register. Type the address in its name with Dina Server.
09:52
That's great.
09:54
So why do we still need wins? Well, in a lot of environments, we don't today. However, as I mentioned before, many applications particularly older applications particularly older Microsoft based applications still need Net bios name resolution. So yeah, you very well may see
10:13
wind server on the network today. Still, honestly, we're trying so hard to get away from that.
10:18
I'd be surprised if you saw that you know very frequently what do we have now? Almost assuredly dynamic Deanna. What dynamic de ns means as a client comes online, it registers. It's fully qualified domain name and its i p address with the D. N s server.
10:35
Okay. And that way, the administer is the administrator doesn't have to manually populate the list of F you peons toe I p's. And in theory, as those records change, D N s gets updated dynamically as well. Obviously not everything all the time works the way that it should.
10:54
And we'll talk about some of those issues in future sessions.
10:56
But this is just a little bit of an intro to Deanna how it's evolved throughout the years and really understand where we are now. Sometimes I think it takes Ah, look, we have to really take a look at where we've come from, So these aren't really our strategies of choice today. Do we still have a host while? Yes, we do.
11:15
And you will still find certain applications. Use that host file. Um, it's always quicker for me to find name resolution locally
11:22
than it is for me to go out and ask another server. So you know that maybe frequently access F judy ends, we might just manually store in the host while but primarily what our clients air using when I goto weather dot com or whether I go to server one cyber ery dot com We're using D. N s. Most likely
11:43
the N s has been configured dynamic,
11:45
so I hope this helps. I hope this gives you just a foundation on which we can begin and please stay tuned for the next part of our multi part series on DNA.

Up Next

Strategic DNS Ops and Security

Domain Name Servers (DNS) are the Internet's equivalent of a phone book. They maintain a directory of domain names and translate them to Internet Protocol (IP) addresses

Instructed By

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Anthony Harris
Systems Analyst and Administrator at SAIC
Instructor