Networking 101

Copyright Priscilla Oppenheimer

Final Exam Study Topics

Note: The Final Exam is comprehensive. So be sure to study the previous study guides as well as the previous quizzes. Don't forget your OSI Model. Here's a review, with additions related to TCP/IP.

#	Name	Function	Devices	Protocols
7	Application	Provides network services to user applications	End-user devices, servers	HTTP, SMTP, POP, IMAP, FTP, SMB, DNS, SNMP
6	Presentation	Handles encoding of application-layer data		HTML, JPG, MP3, ASCII, EBCDIC
5	Session	Establishes, manages, and terminates sessions		NetBIOS, RPC
4	Transport	Provides reliability and flow control for end hosts	End-user devices, servers, firewalls	TCP, UDP, TLS/SSL
3	Network	Transmits packets across an internetwork	Routers, firewalls	IP, ICMP
2	Data Link	Transmits frames across a single link	Switches, bridges, NICs, wireless access points	Ethernet, 802.11, WANs
1	Physical	Transmits bits across a single link; Handles electrical, mechanical, signaling standards	Hubs, repeaters

TCP/IP Transport Layer

Five basic services of the Transport Layer

Segmenting upper-layer application data
Sending segments from one end host to another end host
Establishing end-to-end operations
Providing flow control
Ensuring reliability

Two main Transport Layer protocols are:

User Datagram Protocol (UDP): simple protocol that doesn't actually do all of the 5 basic services.
Transmission Control Protocol (TCP): complicated protocol that really does do all of the 5 basic services

TCP

Sender divides outgoing messages into segments
Recipient reassembles messages
Session establishment: uses the 3-way handshake.
Sender sequences bytes and recipient acknowledges (ACKs) bytes
Recipient checks for errors in received segments
Sender resends anything that is not acknowledged
Sender slows down if recipient gets behind (flow control)

TCP/IP Application Layer

Domain Name System (DNS): Maps names to IP addresses
File Transfer Protocol (FTP): Sends and receives files using TCP
Trivial File Transfer Protocol (TFTP): Simpler way to send and retrieve files (uses UDP)
Hypertext Transfer Protocol (HTTP): Used on the Web
Simple Mail Transport Protocol (SMTP): Sends e-mail to a server
Post Office Protocol (POP): Retrieves e-mail from a server
Telnet: Remote login, sends typed characters to remote host
Simple Network Management Protocol (SNMP): Gets (and sets) performance, configuration, and other data from managed devices

And that's all. Whew! Good luck on the exam!

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