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I am shaky on network setting up concepts.

When I do ipconfig/all on my machine, I get:

enter image description here

I need to set up a basic home network and want to understand these basic things and what is going on.

I want to understand the output of ipconfig and what different things mean.

In particular:

what are these diffferent physical address? their purpose?

There are more than one adapter : ethernet adapter and PPP adapter. Can more than one be active simultaneously? If more than 1 is active simultaneously, system will have only 1 IP address, right?

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migrated from Jul 9 '11 at 10:36

This question came from our site for system and network administrators.

up vote 7 down vote accepted

First, you can have more than one adapter. You have three in your example. You have a typical LAN network card, a mobile network card, and the PPP adapter, which usually means you are connected to a VPN.

As far as the physical addresses go, they are hard-coded into a hardware device, and are used for layer 2 of the OSI model. This identifier is really how a switch/hub determines who network traffic is for. Some devices have ways of over-riding this. They are supposed to be unique on a network, and the first three pairs of numbers/letters are assigned to a manufacturer, and the last three are kind of like their serial number so they can keep them unique.

As you add more adapters, which are connected to a real location, your routing table is built (do a route print command to see it). It dynamically updates this to determine the best route for traffic to take to get to a certain location. So if you have a LAN connection and a Wireless connection both going to the Internet, the LAN connection being faster, will be given priority. In the case of the VPN, it knows that you are trying to get to your work's network, to it will route the appropriate traffic there. If builds these route tables based on the default gateways that are entered manually, or received through DHCP.

Now back to the basics: IP address is pretty basic, but the subnet mask determines how much of your IP address is to be used as network and hosts. In other words, and this is a very complicated subject unless you have studied it, but as an example, if you had a IP address with a subnet mask of, it means that 192.168.1.X is the "name" of the network, and it can have 254 hosts (1-254, with 255 being for broadcasts). The Default Gateway is how you to other networks for a given connection.

DNS provides resolution for an IP address to a Fully Qualified Domain Name, like if you ping it will translate it to

WINS is a type of name resolution, which is more and more going away, but it used in corporate networks for NetBIOS resolution (basically, your computer's name as you entered it when you installed it). Before we used DNS for resolution internally, this is how computers found each other, like how you found the server.

There is so much more I could say, but I am trying to keep this a shade under "War and Peace", but should give you a start at really understanding this. And to anyone, who knows a lot, please realize that certain concepts may have exceptions, which I did not bother to go into more detail about, so please don't ding me.

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Well put. Though, I think I'll wait for the Cliff's Notes or the movie :) – jonsca Jul 9 '11 at 12:10
@jonsca LOL, those ARE the Cliff notes. Want me to detail subnetting? :) – KCotreau Jul 9 '11 at 12:14
Sure, why not. I really did learn a few things. – jonsca Jul 9 '11 at 12:15
One correction - PPP adapters do mean PPP (it's still used by most mobile phones, note "RCOM GSM"). VPN adapters have their own class, although some programs such as OpenVPN install a virtual "Ethernet" adapter. – grawity Jul 10 '11 at 10:08
@grawity Good to know, but I did mean what Windows calls their built in VPN, which is a PPP adapter. I figured that is what she was running from the screenshot. – KCotreau Jul 10 '11 at 12:00

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