We know there are three modes when it comes to a Cisco device.
The first one is the user mode.
This is the one that you can see on your screen at the moment.
To get to the privileged mode, we type the enable command.
Here we go.
The prompt changes.
And now we are in the privileged mode.
Over here, we can do all show commands.
We can manage our files, operating systems.
We can make a backup and reboot our device.
When we type configure terminal.
We go to the global configuration mode.
This mode allows you to configure your router.
You can assign IP addresses, enable routing protocols, change security options, and so on.
If you want to go back, you type exit and exit again to go back to the user mode.
You can press control Z as well to make this process faster.
I hope it makes sense.
It's pretty easy.
Now a few tips to make your life easier when it comes to typing all these commands.
The most important thing is the tab key.
Please make sure that you use the tab key to finish your command.
Let's try enable.
When I type e n a and press the tab key.
Yeah.
The iOS.
The operating system is going to finish this command for me.
I don't have to type the full command.
When I go for configure terminal, I can type conf.
T and then press the tab key.
Ctrl Z.
What's more, I don't have to finish my command.
I can do conf t.
As long as this command is unique, I'm okay.
On the other hand, I cannot say con t.
Because it's going to say ambiguous command.
Well, there is something.
Well, yeah, there are more commands that start with c o n.
Yeah.
That's why I can say conf T and then it's okay because this command is unique.
What if I want to find out what commands are available?
The question mark is your friend over here?
Every time you're confused, you're not sure what to do.
Just use the question mark to show all options, commands, switches and so on.
Going back to our example, icon.
And now I can press.
I can enter the question mark and I can see, okay, there are two options here.
Configure and connect.
Which one do you want?
If I say conf now it's okay, I can press the tab key to finish this command.
Now configure.
Okay.
What are my options?
Well, configure terminal is not the only option here.
I can configure memory network, replace and so on.
Which one do you want?
Well, I want TI.
And as long as TI is unique because it is, then I can say configure terminal.
I hope it makes sense.
It's pretty obvious, pretty easy to follow.
But please make sure that you use these shortcuts and tips when you configure your router because it
will make your life much easier.
Control A takes you to the beginning of a line and control.
E allows you to jump to the end.
You can use the up and down arrow to show all previous commands like a history of everything that you've
typed so far.
So instead of typing conf t again, I can use my up arrow and just find this command.
Everything that I have typed so far.
Okay, we know how to get started with the iOS, with the command line interface.
We know how to go to the privileged mode.
We know how to get to the global configuration mode.
That's okay.
Let's start configuring our router.
We'll change the hostname.
We type hostname and then whatever name we want.
Let's say R1 a.
The host name has been changed.
What else?
Well, here is a small challenge for you.
When I talked about IP addresses, I did show you one command to verify IP addresses on a Cisco device.
Do you remember?
We go to the privileged mode to do show commands Show IP interface Brief.
We can see one IP address over here.
Ten .1.1.101 which has been assigned using a Dhcp server.
I will remove this IP address because I want to show you how you can actually configure this from scratch.
Here we go.
Everything has been removed.
Oh, you didn't show us how?
Yes, I did that on purpose.
Because it will make our lab more interesting if you don't see how to remove everything.
If you want to remove a command, you say no.
So, for instance, if you say IP address ten point, ten point 10.15, if you want to remove it, you
say no IP address.
10.10 point 10.15.
It's pretty easy.
But I want to show you everything from scratch.
Like you got a new router.
Show IP Interface brief.
Here we go.
This is our interface.
Please check our network diagram G zero.
This interface takes us to the internet G zero IP address.
Unassigned method Manual status is administratively down.
What does it mean?
Well, there is down and admin down.
This port has been shut down, has been disabled.
Something that we can miss easily.
This port is down.
It's not going to work.
Conf t.
How can I assign an IP address in my case?
G zero Gigabit Ethernet zero.
This is the port that I'm after.
Should receive an IP address from a Dhcp server.
I have to go to this interface.
Under this interface I type interface gigabit ethernet zero.
My prompt has changed the interface mode over here.
I type IP address and I say Dhcp instead of saying IP address 10.1, 10.10 or whatever.
I don't know what IP address I am about to get.
I will ask my Dhcp server to assign an IP address for me.
We have to bring this interface up.
This interface has been shut down, has been disabled.
We have to say no.
Shut down.
Please be so nice and bring it up.
Start working.
Go and get an address.
We can see a message now.
It's down.
Now it's up.
If you wait around 20 30s, we will get an IP address.
Here we go.
Let's analyze this message.
A log message, something that a router is trying to tell us about.
It says Dhcp, address, assign interface g zero just to use this shortcut.
Assigned dhcp address of ten .1.1.101 subnet mask which identifies we are in the same network.
R1 a.
Control Z.
Use the up arrow.
Show IP Interface Brief 101.
How can I verify if I have access to the Internet?
Well, we can ping something on the internet.
Eight, eight, eight, eight.
Fair enough.
I can ping the Internet.
I can access the Internet.
You can ask, how is it possible you can see an IP address here?
How can I verify if there is a default gateway?
Yes.
In most cases, when you receive an IP address from a Dhcp server, you will receive a default gateway
as well.
We have received a default gateway we can access.
The internet is beyond our discussion here to show you everything in detail.
We will have a dedicated lab.
We have to talk a little more about some concepts.
But yes, we have received a default gateway.
I will show you.
Gateway of last resort.
A default gateway.
I hope you're okay with this pretty basic lap.
We'll try and do the same using packet tracer now.
