How to measure DNS response times per package to build periodical measurements

[zbalkan]

I am trying to measure the impact of the blockers on the latency. I want to measure the same queries before any plugins installed, and after a blocker is installed. The blocking logic would add a latency, but it would be possible to see after a dataset over a period of time. I built the tester and dataset but the measurement part is a bit problematic.

Basically I need to get the time of request received, then the response created, and get the difference. Should I update the StatsManager? Can I get this info with a very light IDnsQueryLogger implementation?

What should I do to get that information?

Thanks,
Zafer

[ShreyasZare]

Thanks for asking. The time taken will depend upon the app that is doing the blocking. The current apps hold data in memory and use it to block requests. The time usually taken is less than 1ms since if you observe the overall response times for queries, it will be just a few milliseconds which includes significant part as delays on the network. Even on a Raspberry Pi 3B, I see <1ms response times for many blocked requests when testing with DNS Client on the admin panel.

So, trying to measure it from within the DNS server wont be much beneficial since it will always be about <1ms except for cases where actual resolution is being done and the request has to wait for a while.

[zbalkan]

So, I should do it over dig or something similar. I created a script that simulates a network with scapy. I'll run this load twice, one with and one without plugins. I'll compare the load on the client side then. Thanks!

[ShreyasZare]

Yes, external test script that does queries over wired network should be good enough.