Welcome to this CertificationKits CCNA training video, getting comfortable moving around in the command line interface. In this CCNA video, we are going to be talking about getting in a user interface; the different administrative modes that you can get into, how to move around in them, possible error messages you might get when configuring the router that you need to pay attention to, some help short cuts, using your control commands to bring up previous commands and make it a little easier to move around in there and the last thing we’re going to be talking about is some things that you can do to the router to make it a little bit easier to work in when you are configuring it to the command line interface.
But as far as the administrative modes go, there are a few different modes. Now it’s very important to pay attention to the modes that you are in when you are working in this environment. As a CCNA, the first mode you are going to g0 to is called “User Mode.” Sometimes you have to get to enter a password to get there and sometimes you don’t depending on how the device is configured. The key to knowing what mode you are in is the symbol right here.
When you are in user mode you would have the router’s name right here where it says user mode and then the symbol would be a greater than symbol and that’s the indication that you are in user mode. The first thing I do is when I’m in the user mode is I get out of it. The reason I get out of user mode is because it can’t really do anything. I can document certain configurations, I can Ping and things like that but it can’t really view everything I need to and I can’t make any changes to the router.
To get out of user mode, I type the command “Enable” and that will take me down to privilege mode. Now I know I’m in privilege mode because that greater than symbol turns into a pound sign. Privilege mode I can do certain show commands which will be going over. I can use copy commands, I can turn debugging on which lets me view in real time things that are happening to the router. If I want to get out of privilege mode and actually make a configuration change the router, I have to go into global mode. I get the global mode by typing in configure terminal which I’ll go in and show you in a moment. In global mode, I know I’m in global mode because I have this config after the name in parenthesis with the pound sign. From there, I can go to multiple different configuration modes. Anything I can figure in global mode is going to affect the entire router. If I type in interface and then in interface what’s going to happen is it will take me to interface mode. I know I’m in interface mode because that says “Config-if.” If I type router rip or Router OSPF or router than a particular routing protocol, it will take me into the routing configuration mode. Again the name of the router would be here and then let’s say config-router in parenthesis with a pound sign after it. Last one… or not the last one but another one would be… let’s say if I would go to one of the line modes like the line console or the line auxiliary port of the line VTY for Telnet. I type line console 0 and that would take me to line mode where I can configure their properties for accessing to the line console. Now if I’m in any of these modes and I hit control-z, what that’s going to do is it’s going to take me back to privilege mode which is nice because this is where I can go in an show my work.
If I’m in interface mode or routing mode or whatever the mode may be and I want to make a configuration change that’s going to affect the entire router, I type in exit and it would take me back to global mode. Any configurations made in global mode affects the entire router and don’t apply to a particular interface. For an example in global mode is where I would give the router a name. About the router prompt and I want to take a look at what mode I’m in. So the mode I’m in right now is user mode and I know I’m in user mode because of that greater than symbol right there. Again, I want to get out of user mode immediately so I type in enable to get on a user mode. Now I don’t necessarily have to type out enable completely. If I type out… type in disable that will get me out of privilege mode back in the user mode. Now watch what happens if I just type “E” and hit enter. I get one of the errors that you will get. You will get possibility of three errors. I get the error ambiguous command. Ambiguous command means there are commands that start with a letter “E” but the router doesn’t have enough information to discern what command I’m talking about. So what I can do is I can use the help inside of the router prompt and I can put “E?” no space after the “E” and just put a “?” right after it and what it does is it’s question marking what letters could come next or what commands start with a letter “E”. In this mode there are two commands that start with a letter “E” enable and exit. So what’s nice about this router prompt is as long as it has enough letters to build… determine what command I’m telling it, I don’t have to type anymore. “E-N” is enough for the router to be able to tell between enable and exit so all I have to do is type in “E-N” hit enter and it takes me to the next mode. Do not try this in a Windows prompt, it’s not going to work. Now, to get to the next mode to get to the global mode, I type “Configure” and watch what happens when I hit tab, I’m typing “conf” if I hit tab and the router has enough details to determine what I’m telling it, it will go ahead and complete the command for me but it will not execute the command and then I type in the word terminal, T-E-R, hit the tab button and it takes me into global mode.
Again global mode is where I can make changes to the device that affect the entire device like giving it a name. So let’s go in and take a look at what happens when I go to give the router a name in global mode. I type “Hostname” and then the name of the router, enter. Here is another error. I typed that inappropriately on purpose, I do know how to spell hostname here. I type the hostname wrong. Host name is all one word but the problem is invalid input detected at marker. What’s nice about this host and everything was fine up into that point but when I got to the letter “N” that’s where the problem is. So what’s nice about this is I can use a control command to bring up a pervious command, control-P or the up arrow in most operating systems and what I can do is I can use my backspace key and I can type in “N?” and question mark will go right where the “N” was and what it does is it tells me how to spell hostname. So it says “Hey, there is only one command that starts with “H-O-S-T-N” and the next letter is not the letter “N” it’s the letter “A” and it’s for hostname command, but notice something it says host and here hostname is the command; there aren’t any other commands that start with “H-O-S-T” and the “N” so what that’s telling me is I’ve already typed in enough for the router to know that I’m trying to actually name the router and I’m using the hostname command and what’s nice about that is I’m a lazy typer, not the best speller so I don’t have to type the commands out completely. The name of the router I do have to type in completely otherwise whatever I type in at this point, that would be the router name so if I typed in C-E-N-T for central, the router’s name is going to be C-E-N-T coming in a cent… I hit enter and the router’s name has changed. So those are two of the errors that we might get. So the two errors we’ve seen so far are the ambiguous command when it doesn’t have enough characters be able to tell what command I’m trying to tell in. Invalid input detected at marker, when I mistype something, let’s say if we can find that last error that we might get. I type in hostname, space, hit enter… what happens now is I get incomplete command. This is the last error you will see and I get this a lot of time from CCNA students. They will type something in, they will be getting errors, not pay attention and when they go back to look at the configuration of the router it hasn’t been done. If you do it right, most of the times it’s going to show up in the configuration so it’s very important to pay attention at the errors. The router is not going to pat you on the back when you do something right, it’s just going to go to the next prompt but if an error pops up you need to pay attention to it because it will kind of give you an idea as far as what you are doing wrong. What we were doing wrong here is we typed hostname but didn’t give it the variable. So again any time I get an error I can go in and bring up the previous command and I can put a space and then a question mark in this case because we got incomplete command, meaning the hostname was right but it needs the name. I don’t know. Maybe I don’t know he needs a name so if I don’t know what it means, I’ll put hostname, space, question mark and it will tell me. To the right, is the description, it says this system’s network name so once the name of the router into the left shows me the format it wants… just wants it in plain text so I’ll go ahead and give the router a name, I’m going to call it essentialbecause the name is not really going to change. Hit enter and notice I didn’t get any errors this time and that means I entered the command correctly.
We’ve taken a look at the error message we are going to get. Let’s take a look a little bit further and we’ve seen this a little bit… some of the help that’s available to us. Now what I like to do is I just use the question mark. Depending on the mode I’m in, the question mark will give me different commands, commands available for that particular mode. If I hit question mark, what’s going to happen is it’s going to scroll up with a list of commands that take up the screen. If I hit enter, that command list will go in one line in a time. If I hit the spacebar, it wills scroll whole additional page. If I want to get out of there, all I have to do is hit any letter on the keyboard and it will take me back to my prompt.
Let’s see how the “Help” is going to do when I want to put it in IP address on an interface. So the command to get… well the first one I want to do is actually go in and look at the router configuration real quick and see what interface we want to put an IP address on. To be able to look at the configuration on the router we have to be in privilege mode as all show commands happen in privilege mode. Into privilege mode, what I need to do is I need to use that control-z. I could have typed exit there which would take me back to privilege mode but control-z will always get me back to privilege mode and that command that I want to use to show the configuration of the router. Let’s pretend I don’t know what it isand let’s use some of the help. I just put a question mark. Now I’m taking a look for it and it is going to be a show command so I see right here, I see show.
So I want to type in “Show” because it will help me show the running system information message description to the right. So what I want to do is I want to leave that command in my sight so I hit any letter to get back to my prompt and what I’m going to type in is “Show” and hit enter. Here is an error, incomplete command. Someone typed in show, this time when I get incomplete command I do show, space, question mark… put a question mark and here are all the things I can show. This is the one that I want. Current operating configuration so I can see how the router is current configured and notice something; this is the only command that starts with the letter “R” on this page right here. So let’s go in and I hit any letter on the keyboard. Type “Show” again brings up my actual show command because I’d already typed that in and I put in our… let’s see if there are any other commands that start with the letter “R”, there aren’t. So if I just type show, space, “R” it’s going to show my running configuration. I’ll hit tab to complete the command and I’m going to hit enter. The nice thing about the running configuration and the reason I’m showing you this right now is because this is a huge help for me so it’s kind of like a help guide as well.
Everything you see in here other than like version 12.1 at the top is a valid command. Everything in here is a global mode command unless you see it subordinate to another command. Let’s take a look at what I mean here. I’m going to go enter so I can go a few lines down and we are going to look at the interface Ethernet 0 right here. So there is an interface on the router, physical interface that’s numbered Ethernet 0. Now what this does is it shows me what I need to do from global mode to go in and configure and IP address on interface Ethernet 0. Since this is all the way to the left, I tell my CCNA students that since it’s not indented, then that’s a global mode command and what that’s showing me is to build and go and put an IP address, I first type “Interface Ethernet 0” in global mode then I go in and write here it’s says “No IP address” so if you want to get rid of a command you’ve done, you put a “No” in front of that command so the command actually put an IP address in here would be IP address and again this is very helpful because if I forget a command or I’m troubleshooting a router, I’ve actually fixed routers before not knowing what I was removing but something didn’t look right in a running configuration so I go in and get rid of it. Obviously I’ll look it up real quick online, Google it to see if it’s something I can remove safely and go in, remove it and it’s a great way to learn commands as well as fix things that looked a little bit funny so it’s a very helpful troubleshooting tool.
Let’s go in and us this help here and configure an IP address on interface Ethernet 0. So I hit any letter on the keyboard and the reason I did that at this point without showing anymore of the running configuration because I’ve already seen what I want to configure here so I’m going to go in and configure it. Now remember, the running configuration, all these commands, valid commands you see here start in global mode. So first I have to get to global mode. I type in configure, again I can use shortcuts, config t for terminal, hit enter and I’m in global mode. Now right here I see interface Ethernet 0 so I’m going to go in and type that in. Enter, hit tab, it completed it, Ethernet, hit tab again it completed it and I’m going to put 0 there for that particular numbered interface and I hit enter just like I’m seeing here. Now in the actual running configuration it says “No IP address” so I’m going to go in and put an IP address but maybe I want t check to make sure IP address is a valid command and so I’ll go ahead and I’ll put a question mark and see if I can see IP in there. I do see IPs so that is a valid option here so I’m going to go IP, space, question mark again and see what commands can come after IP. Now there are quite a few popping up in here and I know I’m supposed to put address so let’s put an “A” and a question mark and see all the commands that just start with a letter “A”. Address is one of them, access group is another. Access group is a command that will play an access list to this interface. We’ll be talking about access list in another CCNA video. Address is what I want to put on here. I want to put an IP address on there. Minimum letters I need to type in, “AD”. So I’m going to “AD” and I’m going to hit enter. Opps! Incomplete command, I got to pay attention to that. I don’t just type in IP address and hit enter, I got to add some additional things. So to look at some of these control codes that we can use, control-P brings up my previous command and I’ll go in… I don’t need to type anything else but I’ll put a question mark here and it actually wants an IP address. So after IPAD is… “Hey, put the IP address in, this is the format I wanted in, A, B, C, D” which is dotted decimal so I’ll go ahead and put an IP address in there and then I’ll make this a gateway address for a local area network. If I think I’m done, I hit enter. Invalid input detected at marker, my CCNA sim is acting a little bit funny here. What it needs next is actually a subnet mask. If I put a question mark here, what happens is it shows me IP subnet mask is what it wants next so if I’m unsure that I have all the components of the command entered in, I’ll go ahead and use the question mark here and I’ll say “Okay it wants he IP subnet mask, A, B, C, D” is the format which is dotted decimal and I’ll go ahead and put in subnet mask in there.
Now, I don’t want to get anymore errors so I do a question mark and see if there’s anything else I needed to type in and what it’s showing me is, the only option here is CR and that carriage return so I can hit enter. Notice I did not get any errors. Again, errors are going to let me know that I’ve done something wrong. If I don’t get any, everything is good. Don’t expect again something to pop up and say you’ve configured the router appropriately; it just goes in and doesn’t tell me that I haven’t done anything wrong. So with user help, check out the running configuration which is a huge help to me. Use the question mark quite a bit, now again let’s take a look at using some of our command editing tools here.
Control-z takes me back to privilege mode and what I can do is control-p brings up previous commands, control-n brings up the next commands so if I’m going in typing commands, I can use my previous commands, my next commands. Let’s say I go back into an interface and I want to go into an interface, Ethernet-0 and I go back to that interface and I want to put the IP address back in but I want to make a change to it. What I can do with this point is I can use control-b to go backward and it will take me backward. Control-f will take me forward. Now I can get all these commands as Cisco’s website but it’s also… I get the same thing just by hitting my back arrow. Back arrow, forward arrow, up arrow brings up the previous command, down arrow brings up the next command so I don’t necessarily have to use the control-p, control-n, control-b for back, control-f for forward. I can also use the up and down arrows as long as the version of HyperTerminal I’m using supports it. A little bit older versions of HyperTerminal that came on some earlier XP versions did not support using the up and down arrows so you’d actually have to use control-b for backward, control-a to go to the beginning of the line, control-e to the end of the line and some of those control commands that you can actually use.
What’s nice about control-a is I go right to the beginning of the line if I want to get rid of this IP address I just type in “No” right in front of that, hit enter, noticed I didn’t get an error here so the command went right and I got rid of the IP address. If I want to verify that the IP address is gone, I type “Show, running config” and I can check underneath interface Ethernet-0 and it says right here just what I typed in, “No IP address” so I was able to remove the IP address. I’ve cleaned up my router prompt a little bit and I want to go over just a couple of commands that I use to make the configuration environment a little but user friendly. One of them is I turn off the IP domain lookup by default and what the IP domain lookup does is allows name resolution for DNS from the router.
Now the problem is if I mistype a command, what happens is the router is going to broadcast for a DNS server and I’m just going to sit there hanging for a minute. With the old no IP domain lookup, what happens when I mistype a command or mistype something that’s rather totally doesn’t recognize, it will go in and just say invalid name and take me right back to my prompt s it’s not going to sit there and hang. So no IP domain lookup will turn that off. Another big thing to do is if I go into my line console, the line console is the port on the back of the router that I use to plug in when I have physical access to the device to configure the operating system so if I’m plugged into the line console, what happens is I get a bunch of pop ups when I go in and configure things and what will happen is these pop ups will interrupt my typing. So by typing in the command, logging synchronous, I tab that out. What that does is no matter what I’m typing or what I’m configuring, it always takes me right back to my prompt. When I do control-z right here, an example of that would be if I were to start typing, it says config terminal, configure from the console” that’s a little pop up and if I’m typing something, my text is going to show up over here on a router prompt but by typing looking synchronous, when this syslog messages pops up. It take me right back to my prompt and makes it a much easier environment to use.
So for a quick little recap of moving around in here, I’ve exited out of the router, the first mode I get into is user mode. Again we’ve got the name of the router and then the greater than symbol that tells me what mode I’m in. Enable is the command to get from user mode to privilege mode but I don’t have to type enable all the way out. If I type “E” and hit enter, I get the error ambiguous command, again meaning the router doesn’t know what I’m talking about. There are commands that start with a letter “E” but there’s more than one of them. So I will hit my up arrow on my router which brings up my previous command and put a question mark without a space and it will show me all the commands that start with a letter “E”. Enable is “EN” there aren’t any other commands in this mode that start with “EN” so I’ll go ahead and hit enter and that takes me to privilege mode. I know I’m in privilege mode because I have the pound sign.
Now from there if I want to actually go in and make any configuration changes to the router itself, I type in configured terminal or config space “T” which again using the shortcuts and it makes it a lot easier. So now I’m in global mode and I know I’m in Global mode by looking at the prompt right here, Central is the name of the router, it says config and then has the pound sign so that tells me that I’m in global mode. It’s important that you know what mode you are in because not all commands are going to work in all modes. For example, show running-config does not work in global mode. The only place that works is in privilege mode, show run or running-config works in privilege mode but not global. So if I’m typing in command that I know is valid like I just typed in show running-config and global mode and I get an error. I want to take a look at the mode I’m in, make sure it’s the right mode for that command and again make sure I’m typing in the command correctly but one of those two things is probably happening if I’m getting an error and I know the command is I’m either mistyping it which the error would tell me this is a mistyped command because there are commands in global mode, that start with a letter “S. But I know show running-config is a good command so I must be in the wrong mode all together. When I’m in global mode, I can actually change configuration of the router, again like the name, anything I do in here will apply to the entire device and here I can go into different modes like I can go into the interface to put an IP address on the particular interface. Interface, “E”, it tab, tab complete the command, Ethernet is the only thing that start with the letter “E” after the interface command in global mode and then I specify the interface number and it takes me to that interface. Again if I’m here and I type in ip add which is short for address and hit enter, if I get that error incomplete command, that means I have to put additional components to the command for this to work. Hit my up arrow to bring up the previous command, if I got too far, I hit the down arrow to bring up my next command and I put a question mark if I forgot what I’m supposed to put. Hopefully I don’t forget I’m putting an IP address after the IP address command, that’s the whole point of that command in the first place. IP address again is the description of the command, A, B, C, D is dotted decimal, that’s the format it wants it in so again I can go in here and put that command or the IP address in but I’m not sure what comes next. I put a space, question mark, IP subnet mask comes next in dotted decimal format.
If I am wondering whether or not I need anything else, question mark right there, I see the carriage or turn that means I can hit enter. Again, no pat on the back for doing it right. All it’s showing you right to the next prompt, I didn’t get any errors so I know I did the command right. If I want to view it, I can either type in exit twice, exit takes me back to global mode, exit again, takes me back to privilege mode. Again exit will take you back one level at a time or I could have just used control, hold control down and tab-z and it will take me back to privilege mode and my command here is “Show”. Again I can tab it out to see the whole command, running-config and it will go in and show me the command I typed in. Remember from global mode if you are looking at the run, I typed in interface Ethernet-0 and then I type IP address 192168.1.1 and then the subnet mask. So everything that shows up in here is a valid command and you can use this to help troubleshoot as well as the help you configure things or make changes to configurations when you know they are inappropriate just by copying what’s in the running configuration.
In this CCNA video, we’ve talked about getting acquainted with the user interface, different administrative modes you are going to bump into, possible error messages, your help, shortcuts, some control commands and some configurations you can do to make the environment a little bit more easier that no IP domain look up and the logging synchronous commands. I hope you’ve enjoyed this CertificationKits CCNA training video on moving around in the command line interface.