Time
31 hours 29 minutes
Difficulty
Beginner
CEU/CPE
30

Video Description

Using the ipconfig and the NS lookup commands This lesson covers using the ipconfig and nslookup command. Ipconfig is the Windows command line that shows generic information about our client such as the network name and which DNS servers we are connected to for a particular adapter. The NSlookup allows us to perform a DNS lookup and see what servers are providing us with a response.

Video Transcription

00:04
next that we have I p config. Now I p config is going to be the Windows Command, which we run a command line, which is going to show us some generic some generic network information about our client. This is going to let us see what I P address is assigned to our different network adapters.
00:22
It's going to see let us see things like which DNA servers that we're currently configured to you for a particular adapter.
00:29
What? The name of the network that we're on is different generic information that is useful for us when we're trying to establish our network identity or for doing some troubleshooting and trying to figure out what our I P addresses
00:40
Now our I p config has a Linux UNIX Mac OSX counterpart, which is I f config.
00:49
Now, all of these switches that we're going to discuss our Onley for I peek and fig. But the general, the generic
00:57
UNIX Lennox command that is going to be the I P config counterpart is going to be I f config. If you type in I p config on a on most UNIX or Lennox machines, you're not gonna get anything back it's gonna be an unrecognized command. And
01:11
but if we type in I f config, then we're gonna get the same type of information on a UNIX or limits machine
01:17
that we would if we typed an I p config on a Windows machine. And then the inverse is also true. We type in i f config on a Windows machine. We're not gonna get anything. We're gonna get an air back that that's not a valid command.
01:27
Some of the switches that we can use for our I p config in our Windows command line are going to be all flushed e and s release and renew Now standard a standard I peek and FIG command is just going to give us again just our general information about our different adapters. It's not going to give us all the detailed information
01:48
such as our Mac. One of the important things we may want to check
01:52
the Mac addresses of our network interface cards, the physical addresses of our network interface cards. In order to get our more detailed information, we'll throw in the switch that ford slash all i p config ford slash all and what that will do is that will return not just the information that we get when we type in i p config,
02:10
but it will also return more detailed information again
02:14
things like our actual Mac addresses of our network interface cards. So if you're looking for certain information from your i p config and you aren't seeing it there and you say, Well, I know someone told me that I need to run an I p config in order to see this information Well, then give I peek and fig space ford slash all a shot
02:34
and you'll notice that there's a lot more information there that's going to give you a lot more insight into your current network connections.
02:40
Next we have our we're gonna go ahead and we're gonna move down to our release Renew now release. Renew our two additional add ons to R. I. P. Config That only work when we have our network interface cards set to automatically obtain I P addresses
02:57
these two commands on Lee work when we're automatically obtaining I p addresses through D h C p.
03:02
What this means is when we run an I p config ford slash release is we're going to release the least I p address that we got
03:14
when we did our d h cp discovered the HCP request command. When we ran our d h e p discovered he actually p requests. Now we would want to run a NYPD config forward slash release When we're in a situation, say where we move to a different network and our computer, it still has an I P address from our old network.
03:32
Then what may be happening is our computer. When we shut it down and moved, it reconnected it.
03:38
It still thinks it's connected to that old network so and its I p addresses not least, is not up. So it sees no reason to try and re run the HCP discover and try to get a new i p address. But it isn't able to connect to the Internet with the current I p address that we have. So it thinks there's a problem with the network, not a problem with its own I p address.
03:57
So
03:59
what release is going to do is it's going to tell our computer. Okay, I want you to release the I P address that you currently have, and just forget it.
04:08
And then following that, we would do an i p config board slash renew command
04:14
and essentially tell our computer to re re perform all of the steps in acquiring and an i p address through D H cp. And we're going to get a new I P address from the network that we are now on.
04:27
So we're going to say, OK, now I want you to renew your i p address and try to get a new one. If we're on the same address that we were already on when we had the old I P address, we may get the same i p address back if our I p address has not. If the lease has not run out on the d h d p server.
04:45
If the server that issued us the I P address
04:46
still has our Mac address associated with that I p address and the lease is not run out, it will say, Okay, your lease hasn't run out. Let me just give you your back your same i p address. But if the lease has run out, then we may get a new I P address or for on a different network with a different I p addressing type. Then we'll definitely get a new, different i p address because we're on different network.
05:06
And again if we have our I P setting set to static. If we have a statically assigned I P address, we run. If we try to run, either this release or renew will get an error message back that will let us know that our adapter is not in the correct state in order to perform these these actions
05:25
because our adapter is currently set to static, so it has nothing to do with D H. C P. It's not automatically retrieving its I p address,
05:31
so it's not going to release a renew that static address because we manually set that I p address. So if you connect to a different if you moved your computer, you connected to a different network. You aren't able to connect to the Internet. So you say, Oh, well, let me try to run an I p config release for new, and you get an error back that says your adapter is not in the correct state, Not
05:50
not,
05:51
and on air that says you can't perform this actions when you have when you have no I p address. If you get an air back that says the act of these these actions cannot be performed. Your doctor is not in the correct state. Then you may want to check your I p configurations and make sure you're not set to statically receive. And I statically set an I p address because if you're statically set,
06:12
then you're not going to be able to pull an I P address the D h c p.
06:15
So make sure you want to make sure you want to check that if you can't run these commands
06:19
and then lastly, we have our flush d. N s.
06:24
Now we talked a little bit about Deanna. Well, we've talked quite a bit about Dean s in some of our previous modules, but this is a quick recap D N S is what is our domain name service. And it's the functionality. It's the service that lets us take Let's resolve host names toe I p address.
06:41
It's what takes www dot cyber dot i t
06:44
and resolves that to the i p address of the Web server that our computer wants to go out and connect to
06:49
now
06:51
our local computer. Our computer has a local D. N s cash that it keeps that way when it's going in trying to resolve host names that I p address, it only has to do the same host name every once in a while. If it goes out in his truck and it tries to resolve a certain host name, it gets a valid I p address back then it'll say, OK, I'll save this in my cash
07:12
so I don't have to go all the way out and wait for a response back later. I'll just already know it. It'll be saved in my record book here,
07:17
but things may change. Maybe a server got moved to a certain server, got moved to a different I P address or maybe website got moved or changed to a different I P address and you try to connect and you're getting your having issues because essentially you're trying
07:35
your computer thinks that this host name
07:39
is on this I p address words no longer at. So in order one of the steps that we can take in order to make sure that D. N S is not what's causing the problem is performing flush V. N s. And what this will do is this will tell our computer. Okay? All these things that you have in your local cash clearem out and start fresh Any any D n s
07:58
look ups that you do From now on, I don't want to check your local cash.
08:01
I want you to actually go to a server and perform queries in order to try to pull the actual new I p address for this this host name. So
08:11
we'll run an i p config ford slash
08:15
flush
08:16
the N s.
08:18
And that's going to flush out the old cash and let us start with a clean slate on. And it may be one of the steps that if you're having trouble connecting to a website, you're having trouble connecting to a server you may have a technician in for me to do or if you are the technician. Ah, and you're having trouble in a certain client is having trouble connecting to a certain server
08:37
or having trouble connecting to a certain website
08:39
that may be one of the steps you want to attempt is running a flush T and s to remove and clear out that d and d n s cash.
08:48
And then lastly, we have r N s. Look up now. We just talked about our flush D N s R s. Look up is going to be what allows us to from the command line perform a d n s. Look up and see. See what servers are providing us with that answer back. So that's that s look up. That's that name service. Look up
09:07
so
09:09
we can run an inn s look up command with just an I p address or a host name qualifier. So we type in In s look up,
09:16
cyber very dot i t.
09:22
And we'll get back on entry. That will show us the i P address as well as the i p address of that. That host name that we're resolving as well as what server? Let us know what that I p address was who is authoritative or whose, if they're authoritative or if they're non authoritative
09:39
for that D. N s domain, authoritative and non authoritative, A little bit
09:43
out of the scope of this module.
09:46
But that s look up, won't let us let us perform in the command line and actual look up for the actual de ns query for a certain host name. And then we can also do reverse lookups are remember, eh
10:01
Host Name to I P address. Look up. If we're trying to look up the i p address associated with the host name that's called a full forward. Look up
10:09
If we're trying to look up a i p address
10:13
two
10:15
If we're trying to look up I p address tau host name that's called a reverse look up because it's reverse of what we're usually doing, but with us, look up, weaken Do either weaken type in the host name or weaken type in i p address. Now, if you just type in in s look up without anything next to it without any qualifier, that's going to drop you into an actual in s look up shelf.
10:35
So anything you type past that is just going to be an additional qualifier on NS. Look up.
10:39
So you type in this look up and then you hit return and it brings you down to a new line and it looks completely different than the line that you were just signed. There's no path associated with it. You just have the indicator that this is where you're at. This is where your typing. And then you try to type in I p config and nothing's coming up. It's an invalid command. Try and type in.
11:00
Try to type in paying and trace route. Nothing comes up.
11:03
Well, that's because you're actually
11:05
in the Ennis. Look up shell and you can type in in us. Look up commands You can type in an I P address. You can type in a host name. Maybe you need to do multiple d. N s look ups. You could just do those here right in a row without actually having the type in its look up. You just type in the host name or i P address and we'll return those answers back to you.
11:22
And that's all good and great. But now we need to get out. We're done with an s. Look out. We're moving on to other commands.
11:26
Well, all we need to tighten now is just exit
11:30
If we're in an ***. Look up, shell. If we just typed in Innis, look up and hit return and dropped down into an anise look up shell, and now it's time for us to jump back out because we want to do other commands. Then you just type in exit E x I t it return and we'll jump back out and you'll notice everything looks the same again.

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CompTIA Network+

This CompTIA Network+ certification training provides you with the knowledge to begin a career in network administration. This online course teaches the skills needed to create, configure, manage, and troubleshoot wireless and wired networks.

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Anthony Harris
Systems Analyst and Administrator at SAIC
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