Testing Network Connectivity

Ok, first up is an article how to simply check network connectivity with "ip config," and help troubleshooting network connectivity issues by using "ping" in a command prompt.

Ping (or Packet InterNet Groper) sends ICMP echo requests to target hosts and listens for ICMP echo replies.  It measures round trip time from transmission to reception, and reports errors and packet loss.

If your ping receives the same amount of packets that it sent, you're good.

OK, so here are some useful network-connectivity-checking commands that can be done from within a command/DOS prompt.

IP CONFIG:

1. ipconfig - Typing ipconfig in a command prompt gives you relevant network connection information (if present) on whatever various network adapters you may have in your machine.  The output includes IPv4 address, Subnet Mask, and Default Gateway.
2. ipconfig /all - This command gives even more detailed ipconfig information including the device's hostname and physical (MAC) address
3. ipconfig /release - This command will release (end) your network connection ip address
4. ipconfig /renew -  This command will renew (re-establish) your network connection ip address
5. ipconfig /flushdns - This command clears the local DNS cache

PING:

1. ping 127.0.0.1 - Pinging this address (also known as the Loopback Address) tests that your TCP/IP stack isn't corrupt (look for four packets sent/received) and tests if your NIC is functioning on the physical level
2. ping <your ip address> - pinging your own ip address (ex 192.168.1.100) tests if your NIC is functioning and that the computer was added to the network correctly
3. ping <your gateway> - This tests if your default gateway is functioning and that you can communicate with a local host on the local network
4. ping <an external address> - tests if routing and your internet connection are working

Take note that if your IP address shows as a 169.254.x.x address, your computer has an APIPA address  (automatically assigned private IP address) and you will only be able to communicate with hosts on your own subnet and cannot be routed anywhere.  This is often due to DHCP being unavailable to the machine.

Here's some additional information from Microsoft TechNet on pinging ip addresses:

https://technet.microsoft.com/en-us/library/Cc940095.aspx