Tag Archives: training

What is Really All About?!?!

It is always so entertaining to see the exact questions that I had when I was starting my Cisco Certification pursuits. First off – congratulations in your choice to study this material – and thank you for reading my blog!!! please consider posting feedback and questions in the comments section. Every question and every comment is responded to promptly.

Now on to the question….

Why do we have the Loopback address and why is it Early on when the Department of Defense in the US was designing TCP/IP, they decided that they should reserve a portion of the space for testing. They rather randomly selected the 127 space for this purpose. In fact – it is the entire space 127 space that they reserved. Many do not realize this, since the most common implementation is to assign So try pinging the address on your PC and it might just respond if your vendor supports testing with other numbers in the reserved loopback space.


What is the fact that your machine responds to really telling you??? This is telling you that TCP/IP is properly initialized on your device. You might not have external interfaces set up properly,but the TCP/IP stack is indeed there and it is functional once you do the remaining required configurations.

Notice the creators of TCP/IP had no idea there would be an IP address shortage when they selected this space! They sure wasted a lot of addresses for this testing purpose.

Remember also that you can create your own loopback interfaces on Cisco devices. For example, you can do this:

interface loopback 101
ip address

This creates a virtual interface on your device that you can use for a wide variety of purposes – like testing a feature!

When is the CCIE – X Changing?!?!

Here is a question I still get very frequently – “Anthony – have you heard anything about the CCIE R&S changing soon???” In fact, you can insert any of the CCIE tracks where you see R&S in the question. 🙂


This post is a reminder of the golden rule that Cisco follows with their CCIE Lab Exams…when they OFFICIALLY announce a change in the CCIE Lab Exam Blueprint for any track, there is a six month counter that starts upon the official announcement. That is right! What a great safeguard in your preparation. Now you know that even if they announce a change, you are guaranteed six months from that announcement before the change actually takes effect.

Notice how I highlighted the word officially. Many times, there will be speculative posts, and even preliminary posts by Cisco themselves. So how do you know what is the official announcement? It will be posted on the CCIE News section of Cisco.com.

For some students this would not be nearly enough time to be prepared if they just started their studies, but for others that are deep in their prep – this is an excellent safeguard.

Happy studies and I would love to see your comments or answer any of your questions here.

CCENT Challenge 1 – Host to Host Communication

Examine the graphic below:



Snow_White sends a packet to Grimm. Grimm then responds with a packet to Snow_White. What is the source IP and source MAC address of this packet when it arrives at Dopey? Answer in the form of : IP address of Fa0/0 of Grumpy and MAC address of Fa0/3 of Happy.

Good luck – you will find the answer posted in the comments section of this blog.