How does windows determine "no internet access"?

When a Windows computer is connected to a network, it will often detect whether or not it has access to the Internet. This is a useful feature which helps the user know whether or not they can access the web, and also allows the operating system to make decisions that are dependent on the availability of an Internet connection.

The first step in determining if a computer has an Internet connection is for Windows to determine whether or not the computer is connected to a network. This is done by using a network discovery protocol such as the Link Layer Discovery Protocol (LLDP), which is used to find out what type of network the computer is connected to. Windows can then determine if the network is a local area network (LAN), a wireless network (Wi-Fi), or a wide area network (WAN).

Once the type of network is known, Windows will attempt to detect if the network has access to the Internet. This is done by sending out a request to a specific domain name, such as google.com. If the request is successful (i.e. the domain name is resolved to an IP address), then Windows will assume that the computer has an Internet connection.

There are a number of other methods that Windows can use to detect an Internet connection. For example, Windows can try to connect to other popular websites such as yahoo.com or bing.com. If the connection is successful, then Windows will assume that the network has access to the Internet.

Windows can also check whether or not the network has access to a specific port, such as port 80 (the default HTTP port). If the port is open, then Windows will assume that the network has access to the Internet.

It is important to note that none of the methods mentioned above are foolproof. For example, if a network has a firewall in place, then it is possible for Windows to falsely detect that the network has access to the Internet even though it does not. Similarly, if a computer is connected to a network but the network does not have access to the Internet, then Windows may falsely assume that the network does have access to the Internet.

As an IT administrator, it is important to be aware of these potential issues and take steps to ensure that Windows is accurately determining whether or not a computer has an Internet connection. For example, if a network has a firewall, then it is important to make sure that Windows is configured to recognize the firewall and not falsely assume that the network has access to the Internet. Similarly, if a network is not connected to the Internet, then it is important to make sure that Windows is configured to recognize this and not falsely assume that the network does have access to the Internet.