Network Basics
Two or more connected devices that share data, resources, and communication rules form this.
network
This OSI layer handles cables, radio signals, light pulses, and raw bits.
Physical layer
This hardware address identifies a network interface on the local network.
MAC address
This transport protocol is reliable, ordered, and resends lost information.
TCP
This security system allows or blocks network traffic based on rules.
firewall
This is the largest global “network of networks.”
Internet
A switch mainly operates at this OSI layer and forwards data using MAC addresses.
Layer 2, the Data Link layer
This logical address allows a device to communicate across different networks.
IP address
This fast, connectionless protocol is commonly used for live video, voice calls, and online gaming.
UDP
This creates an encrypted connection between a device and another network over the Internet.
VPN
A private network used by employees inside an organization is called this.
intranet
A router operates mainly at this OSI layer and forwards packets using IP addresses.
Layer 3, the Network layer
In the building-and-room analogy, the IP address is the building and this is the room.
port number
SYN, SYN-ACK, and ACK are the three steps in this process.
TCP three-way handshake
This server sits in front of other servers, hides them, and can distribute incoming requests.
reverse proxy
A network covering one building, home, school, or campus is classified as this type.
LAN
TCP, UDP, and port numbers belong to this OSI layer.
Layer 4, the Transport layer
Websites using HTTPS normally communicate through this port.
port 443
This globally distributed system stores copies of website content closer to users.
CDN
This method divides data into smaller pieces that can travel through different routes before being reassembled.
packet switching
HTTP and DNS belong to this top OSI layer, where users interact with network services.
Layer 7, the Application layer
The slash-number in an address such as 192.168.1.0/24 uses this notation to show how many bits belong to the network portion.
CIDR
This DNS feature temporarily stores an answer so that it does not need to be looked up again immediately.
DNS caching
Unlike a Layer 4 firewall that sees only IP addresses and ports, this firewall can inspect a full HTTP request and block attacks such as path traversal.
Layer 7 firewall or Web
Application Firewall (WAF)