The following articles can assist you with basic troubleshooting of commonly experienced DNS issues.
- DNS Troubleshooting Guide
- My Domains are Not Resolving
- Error: Your Hostname Could Not be Resolved to an IP Address
- Sorry, a DNS entry already exists, please delete it first (from all servers in the dns cluster) - WHM
The following articles may be helpful for troubleshooting more advanced DNS issues.
- Traceroute, Whois, Ping and Dig
- Wildcard DNS, What is It and How Do I Use It?
- I Need a Dynamic DNS Service?
- Using Managed DNS Hosting with LaunchPad
- Configuring DNS Services - Plesk 12.5
- Setting Default Name Servers in Plesk
- DNS Tab in Plesk Admin Panel
- Do I Need to Change My Name Servers to Use CloudFlare?
- DNS ONLY Edition - cPanel WHM