[Dnsmasq-discuss] Maximum concurrent tcp dns requests with dnsmasq

[Jan Horstmann]

Hi,
it seems that dnsmasq with mostly default parameters can be easily
overwhelmed with tcp dns requests. Even for 64 nearly concurrent
requests some will take longer than a second to be answered [1]. This
gets worse with the number of requests.
Are there any tunables which could improve this?

Regards
Jan


[1]
root at 8cb67b32dabb:/# dnsmasq --version
Dnsmasq version 2.86  Copyright (c) 2000-2021 Simon Kelley
Compile time options: IPv6 GNU-getopt DBus no-UBus i18n IDN2 DHCP
DHCPv6 no-Lua TFTP conntrack ipset auth cryptohash DNSSEC loop-detect
inotify dumpfile
[...]
root at 8cb67b32dabb:/# dnsmasq --no-hosts --no-resolv --local-service --
bind-dynamic --server=1.1.1.1
root at 8cb67b32dabb:/# time dig +short +tcp thekelleys.org.uk @127.0.0.1
85.119.82.65

real	0m0.076s
user	0m0.019s
sys	0m0.016s
root at 8cb67b32dabb:/# for i in {0..63}; do time dig +short +tcp
thekelleys.org.uk @127.0.0.1 & done | grep -c '85.119.82.65'

real	0m0.064s
user	0m0.012s
sys	0m0.010s

real	0m0.074s
user	0m0.009s
sys	0m0.011s

[...]

real	0m0.359s
user	0m0.014s
sys	0m0.004s

real	0m1.190s
user	0m0.009s
sys	0m0.012s

real	0m1.171s
user	0m0.012s
sys	0m0.007s

real	0m1.192s
user	0m0.009s
sys	0m0.011s
64


-- 
Jan Horstmann
Systementwickler | Infrastruktur
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