I love testing out configuration myths.
OK, to be fair they are probably not myths - but many of these suggestions work in very specific situations. I try to caution my friends and clients that blindly following a configuration suggestion can lead to more problems. In other words, your mileage will vary.
When I see a tip or trick that will improve performance, I try to understand what the issue was for the author, what impact the change had and what was their testing methodology.
Ideally I would like to reproduce the test and results to prove that this either worked or that this change made no difference. The last scenario would be if this caused more issues and to back out, but that should be an obvious conclusion and procedure.
In this example I remember reading about Cisco’s ip dns configuration command which turns your Cisco router into a DNS proxy or sorts. This is helpful if you do not have a DNS server locally and if your DNS lookups take a considerable amount of time (i.e. 30ms and higher).
Here’s how a sample configuration looks:
Router1# configure terminal
Router1(config)# ip dns server
Router1(config)# ip domain-lookup
Router1(config)# ip name-server 8.8.8.8
Now the fun part: I captured packets of the following scenarios:
From my Windows computer, I executed the following commands:
Watch the video here:
Tony Fortunato, CCNA, CFNI, CWI
Sr Network Performance Specialist
The Technology Firm
www.thetechfirm.com
Getting things to work better - bit by bit-
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Certified Wireshark and Fluke Instructor
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