[dns-operations] Increase in DNS over TCP from Chrome Browser on Windows 11

[David Zych]

On 3/15/23 11:29, Adam Casella wrote:
> It seems that Chrome is leveraging 1 TCP session per DNS query to prevent tracking of the DNS traffic, which unfortunately does not take advantage of TCP pipelining/multiplexing or out-of-order TCP DNS responses over a single TCP stream.

Hi Adam, thanks for sharing this!

We definitely noticed a dramatic increase in TCP DNS requests circa Mon 2022-11-07, for which I'm grateful to finally have a plausible explanation.

The use of 1 TCP session per query is especially significant because our recursive resolvers have iptables rules designed to prevent them from being monopolized by a single misbehaving client, which includes limiting the number of parallel inbound 53/tcp connections per client IP.  The sudden increase in throttling by that particular iptables rule was quite a surprise.

Thanks,
David

-- 
David Zych (he/him)
Lead Network Service Engineer

University of Illinois Urbana-Champaign
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