OSI Model - Flashcards

1. How many layers are in the OSI Model?

7

What is the primary purpose of the OSI Model?

Provide a framework that explains how data travels across a network

Which layer is the Application Layer?

Layer 7

Which layer provides user network services such as HTTP, DNS, FTP, and SSH?

Application

Which OSI layer is responsible for formatting, encryption, and compression?

Presentation

Which layer starts, manages, and ends communication sessions?

Session

Which layer is responsible for TCP, UDP, and port numbers?

Transport

Which layer uses IP addresses and performs routing?

Network

Which layer uses MAC addresses and is associated with switches?

Data Link

Which OSI layer is responsible for transmitting raw bits (1s and 0s) over cables and signals?

Physical

Which device primarily operates at Layer 2 (Data Link)?

Switch

Which device primarily operates at Layer 3 (Network)?

Router

Which layer uses port numbers?

Layer 4 (Transport)

A technician is troubleshooting an unplugged Ethernet cable. Which OSI layer is affected?

Physical

A switch forwards traffic using which type of address?

MAC address

A router forwards traffic using which type of address?

IP address

Which OSI layer is responsible for reliable delivery using TCP?

Transport

Which protocol is known for speed over reliability?

UDP

Which protocol performs a 3-way handshake before sending data?

TCP

A company wants the fastest possible communication for live video streaming and can tolerate some lost packets. Which protocol should they choose?

UDP

Which OSI layer is responsible for routing traffic between different networks?

Network

A computer communicates with another device on the same LAN using which addressing method?

MAC Address

Which OSI layer is responsible for VLANs?

Data Link

A packet travels from VLAN 20 to VLAN 30 through a router or pfSense firewall. Which OSI layer is performing this task?

Network

Which OSI layer is responsible for encryption and decryption?

Presentation

SSL/TLS encryption is primarily associated with which OSI layer?

Presentation

Which OSI layer is responsible for compression and formatting?

Presentation

A technician needs to troubleshoot a bad fiber optic cable. Which OSI layer should they investigate first?

Physical

A technician discovers a damaged switch port causing network issues. Which OSI layer is most directly affected?

Data Link

A user cannot access a website because the Ethernet cable is unplugged. According to the CompTIA troubleshooting methodology, which OSI layer should you check first?`

Physical

Which OSI layer is closest to the user?

Application

Which OSI layer is closest to the physical network cable?

Physical

Which OSI layer is responsible for starting, maintaining, and ending communication sessions?

Session

A user is browsing a secure website using HTTPS. Which OSI layer is associated with the encryption of the data?

Presentation

Which layer is responsible for moving raw bits (1s and 0s)?

Physical

A switch receives a frame and checks the destination MAC address before forwarding it. Which OSI layer is performing this function?

Data Link

A router examines the destination IP address to determine where to send a packet next. Which OSI layer is responsible?

Network

Which OSI layer is responsible for reliable end-to-end communication?

Transport

Which OSI layer is associated with frames?

Data Link

Which OSI layer is associated with packets?

Network

A user cannot access a file server because their IP address is incorrect. Which OSI layer should you troubleshoot?

Network

A technician discovers that TCP port 443 is blocked by a firewall. Which OSI layer uses port numbers?

Transport

Which OSI layer is responsible for communication between applications?

Transport

A network technician is troubleshooting inter-VLAN routing. Which OSI layer is primarily involved?

Network

A switch is forwarding Ethernet frames using MAC addresses. Which OSI layer is this?

Data Link

Which OSI layer includes protocols such as HTTP, HTTPS, DNS, FTP, SMTP, and SSH?

Application

A technician notices no link lights on a network interface card (NIC). Which OSI layer is the most likely problem?

Physical

Which layer should you investigate if SSL/TLS encryption is failing?

Presentation

Which OSI layer is responsible for establishing, maintaining, and terminating sessions between devices?

Session