DOS Commands - September 2014

IPCONFIG Command

ipconfig
Is used to find out your current TCP/IP settings. With IPCONFIG you can find out your IP Address, find your Default Gateway and find your Subnet Mask. This is a very handy network tool for finding your local IP address.

ipconfig /all
To display all your IP information for all adapters. With ipconfig /all you can also find out your DNS Server and MAC Address. This will show your full TCP/IP configuration for all adapters on your Windows machine.


ipconfig /release
To release your current IP information and obtain a new IP Address from the DHCP server.

ipconfig /renew
Used to renew your IP Address if you have it set to obtain IP Address automatically.

ipconfig /displaydns
This shows your current DNS Resolver Cache Logs.

ipconfig /flushdns
This flushes or clears your current DNS Resolver Cache Logs.

ipconfig /registerdns
The register DNS command updates the DNS settings on the Windows computer. It doesn't just access the local DNS cache, it initiates communication with the DNS server and the DHCP server so it can re-register the network address. You can use this for troubleshooting problems with connection to the ISP (Internet Service Provider), like failing to obtain a dynamic IP address from the DHCP Server or failing to connect to the ISP DNS server.

If you ever wonder "what your IP Address is" you would run an ipconfig as shown above. If you need to find your IP address, default gateway or subnet mask ip config is the tool to use. These numbers can be very helpful when trouble shooting your local network connection. If you have changed your settings but they are not taking place you may try a ipconfig release and renew. If you're having problems resolving to a website you may try flushing your DNS Resolver Logs.

PING Command

In all of these examples "xxx.xxx.xxx.xxx" is an example of a Domain Name or an IP Address. You must fill those out yourself.

ping xxx.xxx.xxx.xxx
To Ping an IP Address you would type the following DOS Command in the Windows Command Prompt. Ping followed by an IP address. That is how you do an internet ping.

ping site.com (web address)
To ping a website you would type ping followed by the website domain name. If you know the websites IP Address you can ping it too.

Ping Command Switches


You maybe use the switches together.
ping xxx.xxx.xx.xx -t
Continuous Ping - It will keep on pinging forever until you hit Ctrl + C to stop it. This can be great for troubleshooting intermittent connections. Just open up a Command Prompt(or 3) and run the continuous ping command on a site like Google.com to see when you're dropping packets. I would also run one on your router and on another site like site.com for a better data sample control group.

ping xxx.xxx.xx.xx -n 10
Number of Pings - The N Switch is simply for setitng the number of pings. By default the ping cmd sends out 4 packets at 32 bytes each.

ping xxx.xxx.xx.xx -l 1500
Size of Packet - By default the packets sent are a small 32 bytes. You can set your own size up to the max 65500 bytes. This can really help for stress tetsing your local network.

ping xxx.xxx.xx.xx -w 5000
Time Out - This is in milliseconds. The timeout by default is 4,000 milliseconds which amounts to 4 minutes. Just seeing if you were still paying attention. It really is only 4 seconds.

ping -a xxx.xxx.xx.xx
Resolves Hostanme Address - This is a great one if you are helping osmoen else and need to find out what router model they are using. You an resolve the host of an IP Adrress with this command. Try pinging your router or your local computer with it. ping -a 127.0.0.1. Not this switch will only work in front of the IP Address.

Ping Command Summary

The Ping command is a network tool used to determine if you are able to send packets between your network computer on the internet to another computer without losing packets along the way. By doing this you can determine if you're online or if a website is down. It also calculates round trip time and Time to Live. This can let you know if your NIC card is working properly and if you're able to reach your router or modem. It can also be used as a network tool for troubleshooting.

Networking Basics Command Prompt

tracert site.com
With Trace route you can trace the path your packets take across the internet from you to your destination. Along the way you can determine the time from hop to hop. You can identify server problems and latency with this tool. It really helps see where the failure is between you and a destination.

nslookup site.com
nslookup xxx.xxx.xxx.xxx

nslookup is a way to get the IP address for a domain name. You can also do a reverse lookup from Domain Name to IP Address. It can be a way to find out if your DNS is properly working or if the site is having problems. You can obtain an IP from a site and try to visit the IP directly, bypassing the Domain Name Servers that would usually resolve the Domain name to IP name.

netstat
netstat can be used to view your active network connections and TCP/IP connections. You can determine what ports are open and being used, what programs are using your ports and what kind of TCP and UDP connections are present. Looking in here for the first time may scare the hell out of you.

netstat Switches
netstat -a Displays all active TCP connections. And TCP / UDP ports.
netstat -e Displays ethernet statistics.
netstat -b Displays all active programs that are listening.


netsh winsock reset winsock reset
netsh int ip reset resetlog.txt TCP/IP reset
netsh is used to reset or rebuild the Windows TCP/IP IP Stack. This can be done if you have a problem with DNS. Say you are able to browse to a sites IP address but not to it's Domain Name. You can find the sites IP by using nslookup mentioned above.

getmac
How do I find my MAC Address you might ask?
If you open up the command prompt you simply type getmac.

arp -a
This command can be used to find out the MAC address of the device you are connecting to. With this information, you can find out what type of router you are connected to by using this website.

Access Command Prompt Codes

The best command prompt trick is how easy it is to access it. On Windows XP, Vista, Windows 7 or Windows 8 just press and hold the Windows Key + R on your keyboard. The other way to access the DOS Command prompt is to simply go to your Windows Start menu, Then go to Run. When the little box pops up you type in cmd. Once the Black Command Prompt pops up you can type any of these commands in and have some fun!

Command prompt Run DOS cmd

After all that seriousness and command prompt operating you should take yourself a break and watch these Networking Computer Nerd Rap videos by Cisco and Scrutinizer. You will love them!