CCNA Training with Chris Bryant

[cielo]

I'm trying to remember some of the CCNA topics and saw some minor thinks (I will complete this errata in time)
1. in video 1c from first CD :
a. converting from decimal to binary : the easiest way to do that is to divide the decimal number repeatedly at 2 and write down the rest; to be more specific I will try with one example :
Converting 172 (base 10) to base 2 (binary) :
172 | 0 -> divide 172 to 2 : the quotient is 86 and rest 0; I write the 86 right under 172 and the rest (zero) after the pipe :

172 | 0
86 | 0
43 | 1
21 | 1
10 | 0
5 | 1
2 | 0
1 | 1
The resulting binary value is obtained from writing the rest value from down to top; In my example 172(base 10) = 1010 1100 (base 2)

b. Conversion from base 2 to base 10 :
In Chris example 1101 1010 is corresponding to 219 decimal value which is not true, the decimal number is 218 : 1 x 128 + 1 x 64 + 1 x 16 + 1 x 8 + 1 x 2 = 192 + 26 = 218

PS : Hope this topic will not offend nobody and must seen as some observations.

[cielo]

In 180 CCNA Tests I found a question that sound like this :
You have three Cisco 2950 switches in VLAN 45. According to the following chart, which of the following statements are true?
Device/MAC Address/Priority
Switch A/aaaa.aaaa.aaaa/32768
Switch B/bbbb.bbbb.bbbb/32768
Switch C/cccc.cccc.cccc/32768

Possible Answers :
A. The default priority has been changed.
B. The default priority has not been changed.
C. Switch A will be the root bridge for VLAN 45.
D. Switch B will be the root bridge for VLAN 45.
E. Switch C will be the root bridge for VLAN 45.
F. Switch B’s BID will appear as bbbb.bbbb.bbbb:32768.
G. Switch B’s BID will appear as 32768:bbbb.bbbb.bbbb.

In the book the correct answers : A, B and G

In my opinion the correct options are :
A - the default priority has been changed because the priority of a switch for a specific VLAN is : default priority + VLAN_ID; here, the default priority is : 32768 - 45 = 32723 which is different from 32768 (the default value for priority)

B - because all the switch has the same priority and the tie is the lowest MAC Address

G - in this way is made up the BridgeID : priority|MAC Address

[ruddog]

Good to see someone posting discussion on CCNA training from Chris Bryant! Could not help to notice you went from binary math all the way to VLAN's. Let me know when you are starting over so I can jump aboard and cruise along with you and discuss such items, as you point out, as well as hopefully clarification on other subject areas.:)

[ruddog]

About 16 minutes into video 1B it is stated a switch while having
one host per port can not have a collision with another host on the same
switch. OK, that was clear until it is stated:

“ The ports are collision domains on to them selves.”

So if asked the following questions how would you answer:
How many collision domains are their in a 12 port switch?
How many collision domains are their in a 12 port switch with one host
per port?

[cielo]

video 2b : Switching
on this video Chris tell us about the different stages that a switch must rich, from blocking to forwarding. He tell at some point that in listening state a switch begin to build it's MAC table which I think is not true : in this state the switch send and receive BPDU and process them but all the frames are discarded. The MAC table is starting to be buildup in learning mode and continue in forwarding stage.

@ruddog : every switch port is an collision domain regardless of how many host are connected to that port

[Chris Bryant]

Hi there!

No offense taken, I am very good but not yet perfect. :)

I wouldn't deviate far from the binary conversion methods I teach; they've helped literally thousands of certification candidates master binary and subnetting.

Having said that, you're correct about the small conversion error in that part of the course - I like to say I put it in there just to make sure everyone was still watching! ;) That's been corrected in the most recent version of the course, and doesn't take away from the methods taught in that section.

Thanks for writing, and all the best to you in your CCNA pursuit!

Chris Bryant
CCIE #12933
http://www.thebryantadvantage.com/

[c88k5blazer]

I’m confused….. I purchased my CCNA training videos a few weeks ago and in the second video “Ethernet Standards and Cable Types” states that you cannot use copper for gigabit Ethernet, when for more then 5 years you have been able run gigabit over cat5 6 7. My confidence in this study material is shaken. Can someone provide me an explanation?:eek:

[Chris Bryant]

Don't be shaken. :) That is a misstatement about copper and Gig, but I'm quite sure you'll find the study material helpful - CCNAs, CCENTs, and CCNPs around the world certainly have!

Chris Bryant
CCIE #12933
http://www.thebryantadvantage.com/

[nod32]

thanks alot