Wednesday, September 3, 2008

The waiting, checking the ego, reviewing bonehead mistakes...

A wise man once said (Tom Petty!) that the waiting is the hardest part. Well I am determined not to make it too difficult. I finally scheduled my lab over the weekend, giving myself more than a few months more time to prepare. I feel very confident right now with what they call the "core" topics. This includes sections I, II and III of the blueprint.

My only real problem I have is making stupid mistakes. Over the last couple weeks I have been documenting them so I do not repeat them. Below are some of them.

Switching and Frame relay:

- Not trimming vlans off all the proper trunks. I did it for two trunks, but missed on another one.
- Did not disable DTP with "nonegotiate", I just used "switchport mode trunk." I have made this mistake multiple times.
- Incorrectly using MST instance 0 for a set of vlans, instead of using a new instance number
- Calculated the burst size wrong on FRTS. I know how to do this, just made a bonehead move.


- Putting networks in wrong OSPF area (they were supposed to be "intra-area" but I read too fast and thought it said "inter-area"). I have made this mistake more than once.
- Forgot to disable auto-summary in EIGRP. Don't know if I would have been marked down. it did not affect my reachability. But I think I should remember to turn it off.
- Forgot send-community on BGP neighbor.
- Applied multicast commands to physical LAN interface when there was a subinterface. I do this with WAN interfaces occasionally too. This is a matter of paying attention where you are in the topology and what the goal of the task is. Had I used proper verification commands I would have noticed this.
-Wrong subnet mask on BGP aggregate. I needed to make it /17 instead of 16. No excuse for this at this stage of the game.

These are some common mistakes that I categorize as "bonehead" because I should never get them wrong. Yet, in every lab I do, they are there. In one case I lost 17 points because of these! I do grade myself hard because there no sense in given yourself credit for something you didn't pass yet :).

Anyways, I hope this list does not grow to big. We all learn in school that those who fail to learn from their mistakes are doomed to repeat them. So my advice is to document and learn why you made the error. The reasons are usually carelessness or reading the task too fast. Sometimes I am just so anxious to move on, I configure something and don't verify it adequately.

So, what does your list look like? :)

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