Troubleshooting DNS issues can often take a considerable amount of time, or not. The issues that can be effected by DNS configuration can be either on the internal network (LAN) or the external network (WAN). Simply put if you are attempting to resolve a connection using anything other than an IP address, even this can be affected, DNS is a good place to start your troubleshooting. There exists many tools for troubleshooting DNS, the following is a partial list;
nslookup. This tool is included with all versions of Windows desktop and server OSs. It always comes with the BIND software package. It provides a way to trace DNS queries and offers many options.
dig. Somewhat easier to use than nslookup and can provide more information for DNS troubleshooting than nslookup can.
dnscmd. Is a command-line interface for accomplishing DNS management tasks, Used in powershell or the command prompt it relieves the necessity of using the gui to perform DNS management tasks.
ping. Most commonly used DNS tool to determine if there is connectivity between any two network nodes. Provides DNS troubleshooting using TCP/IP protocols.
pathping. Provides tracert-like information in a ping-package as well as network latency and network loss.
tracert. Shows the route a packet will take through the network a packet will take to go from one node to another. Similar to the UNIX traceroute command.
ipconfig. A built-in command line tool used to display the information on each network interface card attached to the system. Works on all connections virtual and physical. Also displays DHCP host information.
netstat. Used for DNS troubleshooting to provide more than basic TCP/IP for each interface.
nbstat. Used to provide NetBIOS information.