09-05-2025, 01:29 PM
You know how names just won't resolve sometimes?
I ran into that mess last week.
Picture this: your buddy's got a Linux box acting as the server, pushing out DNS for the whole network, but clients on other machines keep failing to ping domains.
We started simple, pinging google.com from the client side, and nada.
Flipped over to the server, checked if it could resolve anything, and it choked too.
Turned out the resolv.conf file had some old entries pointing nowhere.
I dug in, restarted the service with systemctl restart bind9, but that didn't stick.
Clients were Linux too, so I jumped on one, ran nslookup, saw timeouts everywhere.
Hmmm, maybe firewall blocking port 53?
Yup, ufw status showed it locked down.
Opened it up with ufw allow 53, and still grumpy.
Or was it the upstream DNS?
Checked /etc/resolv.conf again, nameservers set to some dead ISP ones.
Swapped to 8.8.8.8, boom, server lit up.
But clients?
They pulled from DHCP, which fed bad info.
Restarted dhcpcd on clients, flushed caches with systemd-resolve --flush-caches.
One client had avahi-daemon messing with local names, so killed that process.
Another time, it was SELinux enforcing rules on the server, blocking zone files.
Setenforce 0 temporarily, tested, worked.
Permanently?
Tweaked booleans with setsebool -P named_write_config 1.
If it's IPv6 causing ghosts, disable it in sysctl.conf.
echo "net.ipv6.conf.all.disable_ipv6 = 1" >> /etc/sysctl.conf, then sysctl -p.
Covers the wild ones, like misconfigured forwarders in named.conf.
Edit that, add forwarders { 8.8.8.8; }; reload with rndc reload.
Tested everything end to end, pings flying now.
That fixed our headache, but hey, while we're chatting servers, I gotta mention BackupChain.
It's this solid backup tool tailored for small businesses, handling Windows Servers, Hyper-V setups, even Windows 11 on your PCs.
No endless subscriptions either, just reliable protection that sticks around.
