Subnet Mask: It is the logical grouping of network devices who are in proximity to each other in a local area network. This logical grouping helps to increase the efficiency of the networks along with providing good security measures. The importance and use of subnetting can be summed up below:
- Management of IP addresses: In a large network with multiple hosts, the subnetting helps to break it into smaller networks to efficiently organize them.
- Network Traffic is Reduced: Issue with broadcasting in a large network is spamming every device with packets that are not relevant to the task. Subnetting creates smaller networks which limits the boundaries of the broadcast domain, thus increasing network performance and enabling better traffic control.
- Simplifying the process: It is an effective way to keep monitoring device on the networks that results in a simpler and narrower troubleshooting process.
- Control Network Growth: Size is the main factor when planning and designing a network. Subnetting helps to determine the size of your network based on the mask of your subnet, thus helps you to control your network growth.
- Network Security: By dividing the network into subnets, you can control the flow of traffic that will help you to identify threats, close point entries, and target your reactions accordingly.
Wildcard Mask: A wildcard mask is a mask of bits that allows or denies all the traffic from a network IP address. It informs the router which bits in the IP address is required to match the access list or not. The wildcard mask is not exactly the opposite of subnet mask although it may look like the reverse of the subnet mask. The use and importance of wildcard mask can be summed up below.
- 0-bit Match: The 0-bit of the wildcard mask matches everything of the network portion of the IP address.
- Different Range of Targets: It can target a single host (or a single IP address), an entire subnet, an entire network (i.e. Class A, B, or C), a range of IP addresses, and can also target all even or all odd networks.
- Beneficial for Large network: It can work efficiently with a large network with several routers and LAN segments and also ensure only allowable traffic to pass through.
- No Subnetting Required: It can work on a single subnet without the need to breaking into small networks.
- Use in ACL: Wildcard mask is flexible to use as because it uses discontiguous bits for matching bit patters unlike subnet mask that uses fixed bit values.
