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IP Addressing Review

Question: How does a Windows Administrator specify Network Classes (A,B,C) with an associated default subnet mask?
In Windows, network classes (A, B, and C) are defined by their default subnet masks. To specify a network class with an associated default subnet mask, a Windows administrator can do the following:
  1. Determine the network class that is needed based on the number of hosts that will be on the network. A network class A is typically used for very large networks, while network classes B and C are used for smaller networks.
  2. Determine the default subnet mask for the chosen network class. The default subnet mask for a network class A is 255.0.0.0, for a network class B it is 255.255.0.0, and for a network class C it is 255.255.255.0.
  3. Open the Network and Sharing Center in Windows and select Change adapter settings.
  4. Right-click on the network adapter that will be used for the network and select Properties.
  5. Select Internet Protocol Version 4 (TCP/IPv4) and click Properties.
  6. Select the option to Use the following IP address.
  7. In the IP address field, enter the IP address for the network. The first portion of the IP address should match the network class chosen, followed by additional octets that define the specific network address. For example, for a network class B, the IP address might start with 172.16.x.x.
  8. In the Subnet mask field, enter the default subnet mask for the chosen network class.
  9. Click OK to save the changes and close the network properties window.
By specifying a network class with an associated default subnet mask in this way, a Windows administrator can configure the network settings for a Windows computer to match the requirements of the network. This allows the computer to communicate with other devices on the network and access network resources.

Review of IP Addressing, Routing protocols and Subnet masks

1) Depending on the routing protocols used, you can specify IP addresses based on: 1) Network Classes (A,B,C) with an associated classful default subnet mask. 2) Classes with variable length, subnet masks (VLSM) , 3) (CIDR) Classless Inter-Domain Routing with a specified prefix length

2) The Class B default subnet mask is 255.255.0.0. Another way to characterize the default Class B subnet mask is to use the classless notation or 'slash' notation. In the case of the default Class B subnet mask, 255.255.0.0 can be represented as /16. This means that the first 16 bits of the IP address represent the network ID.


3) Class-based networks support a single subnet mask, and are suitable for networks routed by using Routing Information Protocol (RIP) 1.0 VLSM and CIDR support multiple masks or prefixes per network. Both VLSM and CIDR require routers that support more advanced interior routing protocols, such as RIP 2.0 and (OSPF) Open Shortest Path First.

4) Class based IP addresses are split into two portions, 1) network ID and 2) host ID. The subnet mask is used to define which portion of the IP address defines the network ID. The remaineder of the IP address is dedicated to the host ID. The Internet Protocol uses the network ID portion of the subnet mask to determine whether a destination host is local or remote.