DNS Troubleshooting in Linux = 1

Step1:Check the DNS server is configured on Client end or not

check in below file if name server is configured to proper DNS server or not
#vi /etc/resolv.conf

If the client is configured with proper DNS server follow to next step

Stpe2:Ping to DNS server ip address

#ping serveripadd

If pinging is happening proceed with the next step.

Step3:So pinging is happening… then there is a communication path between Server-client, so we have to check weather DNS server is running or not. Here nmap can be used to check what ports opened on server.

#nmap serveripadd

Example:

#nmap 125.22.73.23

this command will give you output what are the services running/ports opened on remote server, if DNS server is running and working fine means you can see DNS port(53) in the list of opened ports.

Step4:Now checking DNS server issue in deep

  • Checking under whom the DNS server is register and its properties .

#whois example.com

  • Checking what server is used to resolve and some basic info.

#nslookup http://www.example.com

  • Checking who is resolving and what is resolving in details about DNS server.

#dig http://www.example.com

 

 

 

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