TCP/IP and the OSI Model

I had already studied TCP/IP and the OSI model for Security+. This paper was a chance to go over them again and explain them in my own words.

TCP/IP uses four layers. OSI uses seven. The main difference is how they divide up the work. Some functions have their own layers in OSI but are grouped together in TCP/IP.

My paper also covered TCP, UDP, and IP. TCP checks that data arrives in order and provides reliable delivery. UDP does not guarantee that the data will arrive. IP handles the addresses and helps get the data to its destination.

DHCP

DHCP was something I recognized from studying for Security+. The assignment helped me understand what it actually does when a computer connects to a network.

A DHCP server gives the computer an IP address. It also provides the other settings the computer needs to communicate. Those include its subnet mask, default gateway, and DNS servers.

Without DHCP, an administrator would have to enter the settings on each computer. Doing that for a whole office would take time. It would also be easy to type something wrong. DHCP lets the administrator manage those settings from the server.

The addresses are given out as leases. A device receives an address for a set amount of time rather than keeping it permanently. An address that is no longer being used can return to the pool for another device.

My paper also covered reservations and failover. Reservations let certain devices receive the same address each time. Failover helps keep the service available if one DHCP server has a problem.

Subnetting

My subnetting paper explained how a large network can be split into smaller networks. A business can put employee computers and servers on separate subnets. Different departments or offices can have their own subnets too.

A computer checks its subnet mask to see if the device it needs to reach is on the same network. If it isn’t, the computer sends the traffic to its default gateway. The router sends it on from there.

I learned why the subnet mask matters when checking a connection problem. If it is wrong, the computer may try to reach a device directly when it should use the gateway. Checking the IP address alone would not catch that mistake.

What I Took Away

Studying for Security+ gave me a starting point for these assignments. I had already spent time learning the terms, and the papers gave me a chance to explain how they work. DHCP stood out because it helped me understand where a computer’s network settings come from.

These topics also fit together. DHCP gives a computer its network settings. The subnet mask helps it figure out which devices are on the same network. TCP/IP lets the devices communicate with each other. Understanding those connections gives me a better starting point when a computer cannot connect.

Research Papers

TCP/IP and OSI Model – Research Assignment 1

DHCP in Windows Server – Research Assignment 3

Subnetting and PowerShell – Research Assignment 5