[16.0] Interleave DNS servers across interfaces inside resolv.conf to mitigate resolver limit issues#5385
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eriknordmark merged 1 commit intoNov 12, 2025
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…te resolver limit issues The Go (and also system) resolver only use up to 3 nameservers from resolv.conf. Previously, we wrote all nameservers for one interface before moving to the next, which could result in a single interface with 3 DNS entries consuming the entire limit. This caused other interfaces to fail DNS lookups with error 'no DNS server available'. To mitigate this, change the resolv.conf generation logic to interleave nameservers across interfaces: first nameserver from each interface, then the second from each, and so on. For up to 3 mgmt ports, this ensures that each interface gets at least one usable DNS entry within the resolver's limit. Duplicate nameservers are still commented out as before. The order of interfaces is kept deterministic to maintain stable output. This is a temporary mitigation of the underlying issue; the long-term plan is to implement our own resolver that can use all configured DNS servers without this 3-entry limit. Signed-off-by: Milan Lenco <[email protected]> (cherry picked from commit 78bf514)
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Description
Backport of #5357
How to test and validate this PR
ZInfoDevicemessage (port info is undersystemAdapter)/run/nim/DeviceNetworkStatus/global.json, looking at theLastErrorfield for each interface.no DNS server availablemessages./etc/resolv.conf.Changelog notes
Interleave DNS servers across interfaces in
resolv.confto mitigate resolver 3-entry limit issues.Checklist