Which guide are you using for your CCNA preparation? I will compare the famous book by Mr. Todd Lammle with Mr. Richard Deal. Everyone suggests Todd lammle for sure and I think it depends how far one can absolutely love it. I did not like it as much as everyone else.

Well here are the things you should know about Todd's guide:

1.He talks about stuff you might have never heard of, yet he promises to tell you about it later in the book  and he tells that in a friendly way, this is frustrating.
2.The book covers over and above CCNA objectives, its good in a way but if our priority is becoming CCNA, those extra topics would kill your time.
3.His style of teaching is OK but not so good on few topics, actually waste of time and energy.
4.For configurations the book rocks, thats for sure. He uses a topology throughout the guide and implements different configurations like RIP, Eigrp, OSPF, interface configurations, IOS etc etc.
5.The book doesn't cover wireless topic effectively, you might get 3 or 4 questions from wireless in the test.
6.Whats beyond CCNA in this book: CNA for switches, IP telephone configs etc. If you've decided to use Todd Lammle's book, its very important to check his website for updates - www.lammle.com

What about Mr. Richard Deal's guide for CCNA?

1.The book is not so famous as Todd's but absolutely rocks!!!
2.You'd just read it like a story, yet the guide does not use informal way of explaining.
3.This guide is near to perfection, starts from the very basics of what a "network" is. So if you're completely new to networking, you will definitely appreciate this guide.
4.There are "Exam Watch" notes in between and they're direct questions from CCNA.
5.You complete a chapter, complete the "inside exam" section and take the "two minute drill"and then take the test, you will nail the subject and will not forget.
6.Configurations are not as good as Todd's but definitely NOT bad.

What now?
If you're confused which one to go for, go for Richard Deal, you won't regret it and if you have enough time you can through the configurations from Todd's guide. Like, after you're done with RIP, EIGRP, you take a look at the configuration section in Todd's guide. But this is redundant cos your labs are already covered in Richard's guide. And use GNS3 for your lab practice.

If you want to do a mixed study from both guides, you might wanna study these topics from Richard's guide for sure to be on safe side:

• Layer 2 Technologies (all about cables and layer 2 protocols)
• VLANs and Trunks(dot1q, ISL, EtherChannel etc)
• Switches and Redundancy (STP, PVSTP+, RSTP etc)
• WAN - Frame Relay, VPN
• IPV6
• NAT
• Wireless

Reminding again, the 'Exam Watch' notes in Richard's guide are answers to direct questions from CCNA.
And for the rest Todd's guide did pretty good including:

• OSI Model but take a look at Richard's on Data Link Layer (LLC and MAC) 
• Subnetting, VLSM, troubleshooting TCP/IP
• IOS and SDM
• Managing Cisco Internetwork 
• IP Routing - RIP, EIGRP, OSPF
• Security 

What is NAT?
Network Address Translation translates your local or private IP addresses to public IP addresses so you can communicate with the internet world.
Why NAT? Because its expensive to buy public IP addresses to each and every computer in a network.

Types of NAT:
Static NAT: This is like one-to-one i.e. your one particular private ip address is always translated to one dedicated public ip address.
Dynamic NAT: This is like many-to-many. Your list of private ip addresses are translated to a pool of public addresses, a public ip dynamically picked from that pool for your private ip addresses.
PAT-Port Address Translation: This is like one to many. Your list of private ip addresses are translated to one public ip address. This uses source port no. of your local network to differentiate individual hosts or computers in your local network. This is also called NAT Overload.

Lab:
Local router:
f0/0 - desktop
f0/1 - vpcs1
s1/0 - border router

Border router:
s1/0 - local router
s1/1 - isp router

Isp router:
s1/1 - border router and f0/0 - vpcs2

• Desktop( MS Loop back Adapter) gets 10.0.0.2   255.255.255.252, GW: 10.0.0.1, DNS:  10.0.0.1
• We will use EIGRP in Local and Border routers for routing protocol, so that desktop and vpcs can communicate with Border router via Local router. We will configure them both routers in Autonomous system no 10 so they become neighbours and exchange topology database.

• Border router should be able to communicate with both public and private networks. With Eigrp, border router is already communicating with our local networks. In real world, all local computers connect to border router and border router knows how to get to ISP router, these settings are given by ISP provider. For this lab, we will need to configure border router ourselves, it needs to know the routes. We can use any routing protocol but because we only have one network 99.0.1.0 to be included in the routing table, since 99.0.0.0 is directly connected, lets use static routing.

• I also used 'ip default-network' command so EIGRP can adveterise it to local router.
• With all the above setup we should be able to succefully ping within our local network and within our public i.e. 99.0.0.0 and 99.0.1.0 network. But we can not ping from local network to public network and thats where NAT comes into picture. NAT will translate our local ip addresses to public ip address so we can communicate with our public networks. We are going to implement NAT overload or PAT in our border router.

• First line creates a pool called 'test' with a range of public addresses. In this case only 99.0.0.1 because we're implementing NAT overload i.e. many-to-one. However, we can use more than one public IP.
• Second line creates a list of our local addresses identified by no. '10' with 'permit' option.
• Third line tells NAT to translate inside addresses that are specified in list no. 10 to addresses in pool named 'test', the 'overload' tells NAT to use port no.'s to identify a particular host in the local network.
• Now we're left configuring interfaces as belonging to inside network or outside network in our border router. In this lab, s1/0 of border router belongs to inside network and s1/1 to the outside.

Verification:

References:
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094374.shtml

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Now, make sure you click the right one below..

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How to install MS loopback Adapter:

• Open Control Panel, double click 'Add Hardware'
• In the 'Welcome to add hardware' wizard, click 'next', choose 'install the hardware that i manually select from a list(Advanced)' and then 'next'
• In the 'Common Hardware Types' list choose 'Network Adapters' and then 'next'
• Select 'microsoft' in the 'Manufacturer' section and 'microsoft loop back adapter' in the 'Network Adapter' section and then 'next' and 'next'

Open your GNS3 with administrative privilege i.e. right click on it and 'run as administrator'

• Add a router and a cloud or a computer (computer symbol if you have configured its type as cloud)
• Rt. click on cloud/computer symbol, 'configure,' in the 'Node Configurator' window select appropriate cloud in the left column (C0). In the 'NIO Ethernet' tab, 'Generic Ethernet NIO(require administrator access)' select 'MS Loopback Adapter' in the drop down list and click 'Add', Apply, OK.
  
• Now in the GNS3 window, connect router's fastethernet(f0/0) to the computer/cloud's interface which is our loop back interface.
  
• Start the router, console it and enter commands as shown in the below picture.

• Change the speed to 10mbps using 'speed 10' command cos MS loopback adapter network type is 'ethernet' which is 10mbps. Thats how it worked me.

 Now lets go to - Control Panel->Network Sharing center->(left column) Manage Network Connections.

• Rt. click on your MS loop back adapter, select properties.
• Select - internet protocol version 4(TCP/IPv4), and then properties.
• Fill in the details as show in fig.

Verification:

• ping your router ( 10.0.0.1) from windows command prompt.

• ping your loopback adapter ( 10.0.0.2) from GNS3 router.

• OR you also could check mac addresses by 'show arp' in command prompt and router console.

P.S. I "disabled my firewall" totally, this is "Must" OR you could also change your firewall rules to accept ICMP requests instead of disabling it totally.
Making this work wasn't easy but I finally found the solution and it worked, you should be able to get this to work too.

This is a simple topology to verify VTP. topology is as shown in the picture. I also used VPCS as pcs.
I used routers as switches in gns3, please be aware that gns3 does not support all of the switch commands ex: port security.

Topology details:
-sw1 - f1/0 is connected to      sw2 - f1/0 which is our trunk link.

-sw1 - f1/1 is connected to Vpcs1( Local port: 30000, Remote host: 127.0.0.1, Remote port:20000)

-sw2  -  f1/1 is connected to Vpcs2(Local port: 30001, Remote host: 127.0.0.1, Remote port:20001)

-sw1 - VLAN 1 IP Address is    172.16.1.1    255.255.255.0

-sw2 - VLAN 1 IP Address is    172.16.1.2    255.255.255.0

-Ping 172.16.1.2 on sw1  and  Ping 172.16.1.1 on sw2 to verify connectivity.

-After creating VLAN 2 in sw1's VLAN database  it should appear in sw2 as well due to VTP.

-Assign port f1/1 to VLAN 2 and give a 'no shutdown' command on both switches.

-Vpcs1 - IP Address is   10.0.0.1/24,  GW-10.0.0.250 (just for syntax).

-Vpcs2 - IP Address is   10.0.0.2/24,  GW-10.0.0.250 (just for syntax).

-Ping 10.0.0.2 from Vpcs1 and Ping 10.0.0.1 from Vpcs2 to verify connectivity.

VLAN 1 is in its own subnet 172.16.1.0/24 and
VLAN 2 is in its own subnet 10.0.0.0/24

Note:

• Each and every interface must be manually turned on by 'no shutdown' command.
• We have to set a VTP domain name and ofcourse, same on both the switches. Only then, we will see the Configuration Revision Value and others parameters being updated in the switches.
  

Now that the topology is ready, please watch the below videos to see how VTP worked.
Please watch in full screen for clear view. Videos are playing rather fast, you might want to pause in between to help.

Part One



Part Two

For a complete tutorial on how to use vpcs in gns3 you can check out Chris's blog here
This post will only help if you're having issues with connecting your vpcs to your routers in gns3.
Did you get this message when u tried connecting router's ethernet port in gns3 to one your vpcs?

206 - unable to create UDP NIO

steps to solve this

1. Start a new project if you're working on a simple one.
2. Otherwise, go to the "working directory"   ---->      where you save your projects and delete your project while your gns3 is still open with the current project.
3. Now you CAN connect the router to your vpcs, check that and  save your project.
   
4. Try to avoid switches in between vpcs and routers when verifying communication between the router and vpcs.
   
5. Once you're connected and made sure  vpc and router communicate, by pinging from either of them, you can add a switch in between.
   

WATCH!

• Careful with the Lport and Rport entries: vpc1 gets Lport: 30000, ip: 127.0.0.1, Rport: 20000
• If Lport: 30000, Rport:20000 doesn't work try with different values, you can go up to vpc9 Lport: 30008, Rport:20008

With the " 206 - unable to create UDP NIO " you'll not be able to connect your router directly to your vpc but you can connect them through a Ethernet switch in between but there won't be any communication. Thats why, to be sure, connect your vpc to your router directly and if it connects, well and good if it doesn't then you wanna start a new project altogether or do steps 2, 3.
I dont think it really matters if I open vpcs first or the gns3 first. In my video i started vpcs after gns3, so.
Watch the video below. Its a simple topology, one router and one vpcs. you'll see how the error shows up and how we can avoid that.

Configuration:
router:
f 0/0 - 192.168.2.1 255.255.255.0
vpcs
ip 192.168.2.2       192.168.2.1     24
(gateway: is the router's f0/0 192.168.2.1).

I will try to help , ask questions in the comments please. Thanks..  video here( Big screen ) or right below.

Hello people,

why look around for a pirated packet tracer. download the gns3 all in one, it is very beautiful and works like a charm in Vista. All your CCNA lab practice, building complex topologies and experiments can be done in GNS3 with drag and drop features. GNS3 works with a real cisco IOS image, so you get to practice each and every possible command.

Prereqs:

• ->First get a Cisco IOS image file from any of your friends who own a cisco router.

Install Telnet client:

• ->Open control panel/Programs/programs and feature OR just type "appwiz.cpl" in the RUN window and hit enter, that will open the 'programs and features' window
• ->In this window, on the left panel click on 'Turn windows features on or off'
• ->That will open 'windows features' window, in that tick mark the 'telnet client' and then click OK. It'll take some time to install the telnet client. Done with telnet client.

Now lets make sure if your telnet client is working: (courtesy: www.thundernews.com)

• ->open command prompt.
• ->type "telnet news.thundernews.com 119", hit enter, if you see 'welcome or connected' your telnet client is working.
• -> If that didn't work you can try with these different port no.'s instead of 119, they are 119, 7000, 8000, 9000, 23, 25, 80, or 3128.

Now the stage is set, lets move on to installing GNS3:

1. Download the gns3 all in one here
2. Click on the downloaded file and run it (installation)
   
3. I'd suggest to choose 4 options in the "components to install"
4. After installation, type 'gns3' in windows start menu bar, click on it, opens gns3
5. You get two options, click on 1
6. In the window provide a working directory path, then click on 'test' button, you should see 'dynamips successfully started', then click apply and then ok.
   
7. Now click on button 2, you'll get "IOS images and Hypervisors" window, in 'image file' section provide the path to Cisco IOS image on your computer. Then click OK and then apply. Depending on the IOS version, the platform and model fields gets automatically populated. Take note of the model. we're done.

Now we're at the GNS3 main window, lets make use of it.

• Now, press Ctrl+Shift+Esc to open 'windows task manager' and minimise it.
• In the left panel you can see all kinds of network devices. Drag a router model which your IOS supports, right click on it, click start.
• From the 'windows task manager' you'll notice that your CPU usage goes upto 60% or even more. To fix this, right click on your router, click 'idle pc', let it calculate a value, choose any one from the list with '*' mark, see if your CPU usage drops down to somewhere around 10%, if not repeat this until it drops and dont forget to be patient for it is possible!
• After that, right click on your router, choose 'console', that opens a telnet session to your router. This is as good as telnetting any real router so now you can use what you learned or do whatever.