So far, the results from the survey I put in Monday’s blog shows that about half of those taking the time to answer would be more inclined to take the ICND1 exam, and therefore get a CCENT cert, than before the announcement of CCENT. That pretty well matches what I’ve been hearing from people the last few months – it’s more tempting to take the 2-exam path today, but it’s not necessarily hugely compelling. But even with the ICND1 exam, time pressure plays a role. So, continuing on this week’s theme of looking at CCENT and its content, today I want to show a example of a type of question you might see on the CCENT exam, and give you a chance to test yourself, and to time yourself, to see how long the question takes. (By the way, this same kind of question could easily be on the ICND2 and CCNA exams as well.)
Don’t look any further if you want to time yourself! I’ve put a question at the end of today’s blog entry, but if you look below and start reading, you’ll impact the time, and you’ll want to get a fair time for perspective.
If you take the time to think the problem through, and time yourself, chime in and comment about it. Was it too easy? What did you think about 1st, 2nd, 3rd when solving the problem? I’ll review how I would’ve attacked it tomorrow – and of course go over the answer as well.
Here’s the survey:
Here’s the question. Start your self timer after you’ve finished reading this paragraph:
“PC1 can ping PC2, but not PC3. There are no layer 1 or layer 2 problems at all in the internetwork shown in the figure. The pertinent router configurations are shown next, with a figure of the network following. Start your timer, and stop your timer once you’ve settled on the real reason why the PC1-to-PC3 ping fails.”
Router configs:
Hostname R1
Interface S0/0/1
Ip address 10.4.10.1 255.255.248.0
Interface S0/1/0
Ip address 10.4.20.1 255.255.248.0
Interface Fa0/0
Ip address 10.4.102.111 255.255.248.0
!
Router rip
Version 2
Network 10.0.0.0
!____________________________________
Hostname R2
Interface S0/0/1
Ip address 10.4.12.2 255.255.248.0
Interface Fa0/0
Ip address 10.4.200.222 255.255.248.0
!
Router rip
Version 2
Network 10.0.0.0
!____________________________________
Hostname R3
Interface S0/0/1
Ip address 10.4.25.33 255.255.248.0
Interface fa0/0
Ip address 10.4.135.33 255.255.248.0
!
Router rip
Version 2
Network 10.0.0.0
Odom, CCIE No, 1624, splits time between writing books for Cisco Press and teaching classes for Skyline ATS. In his 25-ish years in the networking industry, he has worked as as a pre-sale and post-sale SE for a few networking vendors, as well as a network engineer implementing network technology. Wendell has spent the majority of the last 15 years teaching, consulting, and writing about networking technologies, most of which in some way relate to Cisco products. His books include titles on QoS, CCIE R/S, as well as several titles related to CCNA certification, including the September 2007 book CCNA Official Exam Certification Library (CCNA Exam 640-802) (Read a sneak peek of chapter 7). Click for the list of current titles by Wendell.
The Leader in Network Knowledge
am I missing something?
I see not one, but two issues with this configuration. In fact, the problem states that PC1 can ping PC2 and not PC3 but I think there would be communication issues between PC1 and PC2 as well.
PC1 can't ping PC3 because the ports S0/1/0 on R1 and S0/0/1 on R3 are on different subnets.
PC1 would have issues communicating with PC2 because they are each configured with the same subnet (10.4.96.0/21). Therefor communication would not be sent to a gateway address. Even if the packets were sent across, I could see this causing many other issues - particularly with duplicate node addresses on the different lans.
Yep, there was one other problem
Arthur,
Yep, I got in a hurry, and didn't double check. Kudos to you for finding it. So, to the details... yes, R1's LAN IP address and R2's LAN IP address, using the suggested 255.255.248.0 mask, make both LANs be 10.4.96.0/21. So, PC1 wouldn't be able to ping PC2 in the current configuration. Maybe lots of others saw that as well, and it skewed the numbers on the poll. However, to complete the point, the R1-R2 serial link is actually fine as is - it's R1's S0/0/1 to R2's S0/0/1, per the figure, and they're both in 10.4.8.0/21. So, the part that was busted - not on purpose, but my oversight - was that I intended for R2's LAN to use 202 (not 102) in the 3rd octet, putting it in 10.4.200.0/21.
Sorry, and thanks so much Arthur for letting me know so I could get something posted. Maybe I should get a tech editor to look at my blogs, like we do for the books. ;-) Thanks again.
Wendell