Tools for Troubleshooting Network Issues
Ping
To determine if a server is responding to requests, you can use Ping. You provide an IP address or a domain name, and you can see if the host is responding or not.
NSLookup
The NsLookup tool allows you to provide a hostname and request one or more types of DNS records (e.g., A, NS, CNAME records).
Traceroute
If you are curious as to what path your requests are taking, as well as how long it takes to get from point A to point B (as well as intermediary stops), you can use the Traceroute tool.
Dig
Dig is a network administration command-line tool for querying the Domain Name System (DNS). dig is useful for network troubleshooting and for educational purposes. It can operate based on command line option and flag arguments, or in batch mode by reading requests from an operating system file.
Whois
If you are curious as to who the responsible party (or parties) is behind a domain name, the WHOIS query will allow you to query multiple domain registrar's databases. If the owner has chosen to hide their information, you can nevertheless return forwarding information.
Port Check
Port check is a tool you can use to check your external IP address and detect open ports on your connection. It is useful for checking if port forwarding at the router is setup correctly or if the port is blocked by ISP (like SMTP port 25). It can also be used as a port scanner to scan open ports.
Tools for Troubleshooting Email or Email Server Problems
MX Check
As SMTP Diagnostics Tool. MX Check will Troubleshoot your SMTP server to know whether the mail server is configured correctly for receiving your domain emails. It will pinpoint the problems of your SMTP server if it is not configured properly.
Check Email
Check email is a free email verification tool. It helps you validate any email address online for free. Check if mailbox really exists. The advance checking will give you completed details about this email address and its server settings
Check POP3
A free Online POP3 test tool to help you troubleshoot if a POP3 mail server is working. POP3, is the most commonly used protocol for receiving email over the internet. When you use POP3 to check emails, POP3 will pull over all emails from remote servers to your local PC.
Check IMAP
A free Online IMAP test tool to help you troubleshoot if a IMAP mail server is working. IMAP is an Internet standard protocol used by email clients to retrieve email messages from a mail server over a TCP/IP connection. With IMAP to check emails, all emails will remain at remote server.