This would be mostly (*)nix based command

This would be mostly (*)nix based command set - Here we go...

1. ping {hostname}

Lets you check whether your internet connection is alive or lost

Example : ping techflock.blogspot.com

2. traceroute {hostname}

Lets you trace packets and find if your connection is broken beyond your ip address. Also can be used to track the number of hops to get to the hostname

Example: traceroute techflock.blogspot.com

3. ifconfig

Find out your ip address, your network interfaces, transferred and received data information

Example : ifconfig

4. nslookup {hostname}

Find out the dns name resolves to a IP - a way to test your dns server

Example: nslookup techflock.blogspot.com

5. dig {hostname}

Does the same as above and provides other dns related information

Example: dig techflock.blogspot.com

6. netstat -a

Find out all the open ports on your machine

Example: netstat -a

7. netstat -nt

Display all the tcp based established connections on your machine

Example: netstat -nt

8. telnet {hostname} {port}

Telnet or connect to a machine at the specified port to find out whether that machine/server is working right

Example: telnet techflock.blogspot.com 80

Ofcourse, there are many other options within each of these commands which you can find out through the manual pages by typing man {command}

Update: Some of the commands might be in /sbin or /usr/sbin paths and might not be in default PATH. So go and execute it from there! For Example: /sbin/ifconfig