the internet Flashcards
(23 cards)
describe the limited connectivity before the internet
dedicated leased lines for high cost
connections
telephone based connection
isolated local networks with minimal external communication
describe the challenges before the internet
limited interaoperability
expensive and low-speed data exchange
no universal communication standard
describe the leased line concepts
▶ A and B share a dedicated line to reach C and D.
▶ High-cost but reliable for direct communication.
▶ Limited scalability as more nodes join
in a leased line, how can a talk to c and c talk to b at the same time
by sending small packets of data
describe ip packet structure
each packet consists of a data and header
header helps routes, fragments and post packets efficiently
packet switching ensures interleave and reliable data transmission
what was the problem with arpanet
1974- handling 3 million packets a day
packets -> lost or arriving of order
solution needed to ensure reliable data transmission
what was the solution to arpanet packet loss problem
TCP
what does tcp stand for
Transmission Control Protocol)
describe tcp
TCP runs on top of IP, ensuring lost packets are retransmitted.
Establishes a connection-oriented communication model.
Guarantees ordered, complete, and error-checked data transfer
describe problem of remembering ip addresses
▶ IP addresses are hard to remember (e.g., 212.58.226.141).
▶ People prefer using domain names (e.g., news.bbc.com).
what is solution to remembering ip addresses
DNS(domain mapping system)
▶ DNS translates names into IP addresses via a hierarchical system.
▶ Requests first go to the ISP’s DNS resolver, then higher-level DNS servers.
▶ The authoritative DNS server provides the correct IP.
▶ In Europe, many DNS queries are routed through RIPE NCC in Amsterdam.
why ports matter
Tcp allows multiple connections using ports
each connection is uniquely identified by a tcp socket
defining a tcp socket
▶ A TCP connection is defined by:(Destination IP, Destination Port, Source IP,
Source Port)
▶ The destination port depends on the service:
* Web (HTTP) → Port 80, Secure Shell (SSH) → Port 22, DNS → Port 53
▶ The source port is usually chosen randomly.
how does internet communication work
▶ Internet communication follows a
stack of protocols.
▶ Each layer depends on the layer
below to send and receive data.
what are the layers of the internet protocol stack (top to bottom)
application layer
transport layer
internet layer
link layer
what does the application layer do
handles user - facing applications
webmail,FTP,DNS
what does the transport layer do
(actual transporting)
manages end to end connections
e.g TCP,UDP
what does the internet layer do
route packets across networks
(checks where it is going)
IP,ICM,Routing
what does the link layer do
manages physical netowrk connections
(ethernet put into computer)
Ethernet,WI-FI,ARP
what is a mac address
MAC Address (Media Access Control)
▶ Unique to each device, assigned by the manufacturer.
(hardware address that identifies you)
▶ Example: 48:D7:05:D6:7A:51
what is an ip address
IP Address (Internet Protocol)
▶ Identifies devices globally across networks.
▶ Example: 147.188.193.15
what is a NAT
NAT (Network Address Translation)
▶ Private IPs (10..., 192.168..*) are not unique.
▶ NAT enables multiple devices to share a single public IP.
