📖 ~1 min read
Table of contents
Symptom & Impact
Applications inside jail fail outbound requests due to unresolved hostnames.
Environment & Reproduction
Typically appears after jail template updates or custom nullfs mounts.
jexec host freebsd.orgRoot Cause Analysis
Jail lacks valid /etc/resolv.conf or network egress policy blocks DNS.
Quick Triage
Check resolver file and test direct DNS server reachability.
jexec cat /etc/resolv.confStep-by-Step Diagnosis
Inspect jail fstab/nullfs mapping and NAT/firewall rules for UDP/TCP 53.
sudo service jail status
Solution – Primary Fix
Provide valid resolv.conf to jail and restart jail networking context.
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sudo cp /etc/resolv.conf /path/to/jail/etc/resolv.conf && sudo service jail restart 
Solution – Alternative Approaches
Use local unbound in host and point jails to loopback-forwarded resolver.
Verification & Acceptance Criteria
Name resolution and package fetch operations succeed inside jail.
Rollback Plan
Revert jail config to previous mount and networking profile.
Prevention & Hardening
Template jail DNS config and validate in post-deploy checks.
Related Errors & Cross-Refs
May coincide with VNET interface routing or default gateway misconfiguration.
Related tutorial: View the step-by-step tutorial for freebsd-15.
View all freebsd-15 tutorials on the Tutorials Hub →
Browse all common problems & solutions on the Tutorials Hub.
References & Further Reading
FreeBSD jail networking and resolver configuration guide.
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