Troubleshooting DNS performance
In this recipe, we will see how to troubleshoot DNS performance-related issues like slow responses. We will see how Wireshark can be used to analyze such issues.
Getting ready
DNS performance is measured by utilizing the timestamps on DNS request and response packets. In order to measure the performance, Wireshark should be connected and capture the DNS packets as close as possible to the client.
How to do it...
How will you know that this is the problem?
- When you are browsing the internet and getting very slow responses, perform the following steps:
- Port mirror the connection to the internet and check if you have any bottlenecks on the way to the internet. You can use I/O graphs for this purpose, as described in Chapter 6,Using Advanced Statistics Tools.
- Verify that you don't have a significant number of retransmissions or duplicate ACKs indicating a connection problem.
- Verify that you don't have any window-related problems, such as zero window or window full.
- If...
