Start->Run->cmd, press enter. In the cmd window type ipconfig and press enter. You will see all required information for all network adapters connected to your computer.
Because they need a device to communicate with a distant network through. These devices are called gateways, and are normally routers. The hosts on a segment need to have knowledge of the gateway device in order to communicate outside the segment. In most environments, the local network will have an internal addressing scheme, one that is not routable on the internet, so there needs to be a device that can translate the internal addresses (non routable on the internet) into external addresses (routable on the internet). Of course this device needs to be connected to both the internal network and the external network to be able to send traffic between them.
The internet connection is actually through your default gateway router. Just make sure your network settings point to that router to get an internet connection.
gateway
To hide a Gateway or Internet Provider address on a Mac computer, use incognito mode. In the settings menu for history, check the box next to the phrase "incognito".
The gateway is determined by the network settings, and is different for different networks.
You're referring to a WEP/WPA/WPA2 key. These aren't on your Xbox, they are actually Passwords for your router/wireless internet. You can get these from your network settings on your computer if using Windows 7, on the router itself, or if you have a Gateway, check the gateway or contact your Internet Service Provider.
It may be blocked by a firewall, or there actually may be some type of problem. You need to check on the router, and the gateway that is being used for Internet access. Check your own settings as well. If the default gateway address is missing then you will not get Internet access no matter what you do.
Gateway is internet term that is used to remove unnecessary traffic or load from internet.
4 address should be added
You have to use a gateway to connect to the internet. You can have your own LAN (local area network), but without a gateway, you don't have a way to connect to the internet. If you want to get technical, wikipedia has a good article.
DNS
There isn't one. The switch only knows about MAC addresses, and the default gateway isn't one of those addresses.