Lecture Notes on OSI and TCP/IP Models

These flashcards cover essential concepts from the lecture on the OSI and TCP/IP models, including definitions, layers, functions, and components of DNS.

What is the OSI Model?

A conceptual framework used to understand and standardize how different computer systems communicate over a network, divided into seven layers.

What are the seven layers of the OSI Model?

Application, Presentation, Session, Transport, Network, Data Link, Physical.

What is the main purpose of the OSI Model?

To help understand how data moves between systems and the function of each layer.

What organization developed the OSI Model?

The International Organization for Standardization (ISO).

What is the TCP/IP Model?

A practical model developed for the Internet with four layers: Application, Transport, Internet, and Network Access.

How does the TCP/IP Model correspond to the OSI layers?

Application in TCP/IP maps to OSI Application + Presentation + Session, Transport corresponds to OSI Transport, Internet corresponds to OSI Network, and Network Access corresponds to OSI Data Link + Physical.

What are advantages of the OSI Model?

Standardization, interoperability, modularity, simplifies troubleshooting, flexibility in protocol design, and educational usefulness.

What does the Application Layer do in the OSI Model?

It provides network services directly to user applications and enables software like browsers and email clients to communicate.

What protocols are examples of the Application Layer?

HTTP, HTTPS, FTP, SFTP, SMTP, POP3, IMAP, and DNS.

What is the role of the Presentation Layer?

It translates, formats, and encodes data for proper understanding by the receiving system's Application Layer.

What functions does the Session Layer perform?

It manages sessions, establishes, maintains, and terminates communication between computers.

What is the primary role of the Transport Layer?

To ensure end-to-end communication and reliable data delivery between devices.

What does the Network Layer do?

It handles routing and forwarding of data packets across different networks.

What is the function of the Data Link Layer?

It is responsible for node-to-node data transfer and ensuring accurate data transmission over a physical link.

What does the Physical Layer define?

It defines hardware elements and the electrical or signal specifications for communication.

What is the Domain Name System (DNS)?

A hierarchical and distributed system that translates domain names into IP addresses, facilitating communication over the Internet.

What components are part of the DNS?

DNS Resolver, Root Name Server, Top-Level Domain (TLD) Server, and Authoritative Name Server.

What are Root Servers in DNS?

They are special DNS servers forming the highest level of the Internet's domain name hierarchy, directing queries to correct TLD servers.

What is Forward Lookup in DNS?

Finding the IP address associated with a domain name.

What is Reverse Lookup in DNS?

Finding the domain name associated with a given IP address.