Essential computer science theory

Application

• creates HTTPS request

• DNS turns input into IP

Protocols: HTTPS, DNS, SMTP

Transport

• splits into segments

• add source and destination port numbers

• use TCP to transport segments

protocols: TCP, UDP

Internet

• adds source and destination IP addresses, creates packet

• routers choose path

device: router

protocols: IPV4/6

Network Access

• adds mac addresses, creating frames

• convert bit to physical data

• sent over

devices: switch, modem

protocols: ethernet, wi-fi

layer 7

Application (data)

• interface between user and network

Protocols: HTTPS, DNS

layer 6

Presentation (data)

• translation, encryption, compression

protocols: JPEG, MPEG

layer 5

Session (data)

• starts, maintains, and ends connections

layer 4

Transport (Segment)

• end to end delivery

• ports, error and flow control

protocols: TCP, UDP

layer 3

Network (packet)

• local addressing and routing

device: router

protocol: IP

layer 2

Data Link (Frame)

• physical addressing, error detection, delivery within the network

device switch

layer 1

Physical (Bits)

• transmit raw bits as signals

device: modem

protocol: usb, ethernet

what are the framework for developments?

investigate, design, develop, evaluate

investigate

figure out what clients need

design

plan solution

develop

write code

evaluate

user acceptance

what are the sorts?

bubble, insertion, selection

bubble sort

compare neighboring items, not used much

insertion sort

take item and insert into right place, good for small nearly sorted data

selection sort

find smallest and swap to the right place, good because less comparison but always quadratic