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67 Cards in this Set
- Front
- Back
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Hosts
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Devices that are hooked up to the internet
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End System
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Devices that are hooked up to the inernet
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What is tranmission rate measured in
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bits/seconds
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Where are routers used
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network core
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link-layer switches are used where
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access networks
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ISP
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internet service provider, allow end systems access to the internet
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TCP
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transmission control protol, how applications talk to eachother
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IP
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Internet Protocol, format of packets that are sent and received among routers and end systems
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RFC
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request for comments
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API
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application programming interface, specifies how a software piece on one end system asks the internet infastructure to deliever data to another end system
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protocol
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defines the format and the order of messages exchange d between two or more communicating entities, as well as the actinos taken on the transission and or receipt of a message or other event
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Client program
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program running on one end system that requests and receives a service from a server program
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distributed applications
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a client program on one computer and a server program on another computer
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DSL
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Digital Subscriber Line
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PON
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Passive Optical Networks
Similar to cable, one fiber cable, split near homes, OLT on server side and ONT on user side |
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OLT
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Optical Line Terminator - Used on client side in PON
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ONT
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Optical Network Terminator
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Guided media
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Waves are guided along a solid medium such as a fiber-optic cable, twisted-pair copper wire or coaxial cable
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unguided media
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waves propagate in the atmosphere and in outer space such as wireless lan or digital satelite
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FDM
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Frequency-Division Multiplexing, the link dedicates a frequency band to each connection for the duration of the connection
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TDM
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Time-Division Multiplexing - Line is broken into circuits, each time frame a end host gets the whole bandwith
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Bandwidth
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Width of the band, with FDM means how big the frequency range is. Bandwidth split
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Packets
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Long messages are broken into smaller chunks of data
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Store-and-forward transmission
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Switch must receive entire packet before it can begin to transmit the first bit of the packet onto the outbound link
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Statistical Multiplexing
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On demand sharing of resources as demonstrated in packet switching networks
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How do packets make it to destination?
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Use a forwarding table, split ip address into sections and get closer each time
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tier-1 isps (3)
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1.) Directly connected to each of the other tier-1 ISPs
2.) Connected to a large number of tier-2 ISPS and other customer networks 3.) International in coverage |
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Tier-2 Isps
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Regional or national coverage and only connects to a few of tier-1 isps
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POP
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points of presence - group of one or more routers in the ISP's network at which routers in other ISPs or in the netwrkings belonging to the ISP's customers can connect
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Processing Delay
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How long it takes the router to process the information and determine where to send the packet - Fixed
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Queing Delay
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How long the packet sits in the router's queue. Variable
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Transmission Delay
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How long it takes the packet to get on the link - Fixed
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Propagation Delay
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How long it takes the packet to move from end-host to another
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Throughput
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Amount of work that a computer can do in a given amount of time
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Bandwidth Vs Throughput
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Bandwidth - Theoretical amount of data that can be sent on link
Throughput- In practice amount of data that is being sent |
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5 layer internet stack - And what information is called in each
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Application - Message
Transport - Segment Network - Datagram Link - Frames Physical |
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Virus
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Malware that require some form of user interaction to infect the user's device
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Worms
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Malware that can enter a device without any explicit user interaction
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Trojan Horse
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Malware that is a hidden part of some otherwise useful software
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Dos
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Denial of service
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DDos
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Distributed Denial of Service
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Transport Services availble to applications
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1.) REliable Data Transfer
2.) Throughput 3.) Timing 4.) Security |
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UDP
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user-datagram protocol
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HTTP
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Hyper Text Transfer Protocol
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POP3
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Post Office Protocol
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IMAP
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Internet Maill Access Protocol
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DNS
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Domain Name System
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Root DNS Servers
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13 in the world
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Top level domain servers
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Responsible for com org net edu gov
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Authoritative DNS servers
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Organization with pblicly accessible hosts must provide these
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Recursive DNS servers
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No information back to host, keeps going until answer then comes back through all servers
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Iterative DNS servers
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Information back to host about where to go next
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DHT
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distributed hash table
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Transport Protocols can not provide what services
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Bandwidth or Timing gurantees
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What services can a transport protocol provide
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Reliable data transfer, throughput, timing, security
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What are avaiable options for an HTTP Request Message
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GET, POST, HEAD, PUT, DELETE
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The date field in an HTTP Response message means what
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The date the response was generated
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The last modified field in an HTTP response message means what
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The time the object was last modified or created
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How do cookies work?
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1.) Server generates ID for user
2.) Creates database entry for ID 3.) Includes ID in response 4.) Client Stores hostname and cookie id value locally 5.) Each request message includes cookie value |
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How do Caches Work
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Install a cache between clients and web server. Link between clients and web server has a super fast link so most connections go through cache first and if object needs to be updated, cache requests from server
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Conditional Get
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Cache uses a Last-Modified get to see if an object has changed. If not, empty message body with response 304
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conection socket
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Servers dedcated socket when making a tcp connection
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stream
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sequence of characters that flow into or out of a process
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UDP has how many bytes in header?
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8
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5 SMTP commands
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HELO, QUIT, MAIL FROM, RCPT TO, DATA
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protocol
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Defines the format of messages, the order of messages and actions taken when receiving messages
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MIME
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Multipart Internet Mail Extension.
Defines data types in ascii format so they can be sent over email |
