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I'm encountering an issue with DNS resolution not working as expected.

Relevant Configuration/Setup:

Operating System: CentOS 7
Server Software: BIND for DNS
Network Configuration: Subnet configurations
Hardware Specifications: Intel Xeon Gold 6140, 18 cores
Troubleshooting Steps Taken:
I have already tried restarting BIND, checking firewall settings.

Logs/Error Messages:

/var/log/messages:

Mar 11 08:30:00 kernel: DNS resolution error - Failed to resolve domain 'example.com'
Mar 11 08:30:05 named[PID]: DNS request timed out for 'www.example.com'
Mar 11 08:30:10 named[PID]: Named service restarted due to DNS resolution failure


/var/log/bind.log:


Mar 11 08:30:05 named[PID]: Warning - DNS query failed for 'mail.example.com'
Mar 11 08:30:10 named[PID]: Error - Unable to establish a connection with the DNS server

Questions:

Has anyone encountered a similar issue in a [CentOS 7] environment?
Are there specific logs or configurations I should check for more information?
Any recommendations on additional troubleshooting steps?

Thank you in advance for your expertise and assistance.

HBruijn
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Bob Lewis
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  • Resolving on Linux is always configured via one or more nameserver entries in /etc/resolv.conf - Commonly you see either external name servers, a local IP-address or nameserver 127.0.0.53 which indicates that systemd-resolved is used. - You then test the health of all of those name servers i.e. dig @ip-of-nameserver www.example.com with your own domain names and internet domain names. If those don't respond, do further troubleshooting there - When you're running bind and example.com is your own domain, check the bind service healt, bind log files – HBruijn Mar 11 '24 at 10:14

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