1.3.3 Networks Flashcards
(19 cards)
Characteristic of networks
() 2 or more computers connected together that can transmit data
Protocols
() Rules defining how devices communicate with each other
() Needs to be standard so manufacturer doesnt matter
TCP/IP Stack desc
() A stack of networking protocols
Protocol layering
Application: Specifies what protocol needs to be used, converts into sendable format.
Transport: Splits data into packets and labels the packet with port number
Internet / network layer: Adds sender and reciever IP address, routers use IP to send packets
Link:
() The physical connection between devices
() Adds MAC address to identify Network Interface Card
Recipients computer
May occur in reverse
LAN Advantages
+ Share hardware (printers)
+ Share files (Access files from any machine)
+ Share internet connection
+ Central backup / storage
LAN Disadvantages:
- Hardware failure big affect
- Access to data can be slow with traffic
- A lot of maintenance required to keep software up to date
Protocol List:
HTTPS: Web content + Encryption
FTP: Transfer files (Authentication provided)
IP: Routes packets
TCP: Reliable stream of packets
SMTP: Transfer emails
DNS Components:
DNS resolver: The first stop
Root server: DNS asks root server to find top level domain (.com, .gov ect)
TLD server: TLD stores information about the domain
Authoritative DNS server: Given by the TLD server which gives the resolver the IP of domain
Circuit vs packet def
Circuit:
() Direct link established
() Maintained for entire conversation
() Data is transfered and received at the same rate
Packet:
() Packets are not limited to single route
Packet vs Circuit eval
+ If one path breaks there are other connections
+ Bandwidth is not wasted
- Requires reassmbly and error-checking
- Not ideal for video calls (can cause delay)
Protocol Layering Advantages
+ Breaks tasks into manageable units
+ Each layer only communicates with adjacent layers
+ Layers can be modified separately
Packet structure
Header:
() Sender and recipient IP address
() Protocol
() Order
Payload:
() Raw data
Trailer:
() Checksum (Verify data)
Firewall
() 2 NIC cards between user and Internet
() Passes between and compared with PACKET FILTERS (rules)
() Rejected: Alter to sender of error
() Dropped: No alert
Proxies
() Collects and sends data on behalf of user
+ Anonymity
+ Reduce overall traffic
+ Prevent access to irrelavant information (school)
Encryption
() Data is unreadable if intercepted
() Keys
Network Security Types:
Computational:
Firewall: Monitor incoming traffic
Anti-Virus software: Neutralizes viruses
2FA: Extra authentication
Social:
Employee training
Secure passwords
Regular updates
Network Hardware
Router: Joins networks together (LAN) by detirmining best path for packet, built in firewalls, can connect LAN to WAN
Hub: Connects multiple devices in a network, sends data to all devices
Switch: Connects multiple devices in a network, sends data to specific devices (Has a lookup table with MAC address)
Modem: Enables communication by encoding and decoding data (analogue, digital)
Ethernet Cables
Fibre-Optic Cables
NIC: Has a MAC address to receive packets
WAP: Receives and transmits wifi signals
Gateway: Translate protocols by beheading and reheading
Client-Server vs Peer-Peer:
Client-Server vs Peer-Peer:
Client to server has better central management
Client to server has better scalability
Client to server is dependent on a single server (it could crash)
Client to server is more expensive to maintain
