Comp2-the structure of the internet Flashcards
What is the internet?
A network of computer networks and computers using unique IP addresses and TCP/IP
What is a gateway?
connects networks that use different link layer protocols.. So that packets can be translated into compatible forms.
what is a router?
connects networks that use the same link layer protocol.
what does IP stand for?
Internet protocol
What does TCP stand for?
Transmission control protocol.
What forms the core backbone of the internet?
Europe, n.america, central and s.america, far east and the pacific , all have high speed connections which interconnect routers.
What is a computer network?
Machines called hosts and devices connected via communication channels.
What is LAN?
local area network- a collection of connected computers on a single site.
What s WAN
wide area network- a collection of connected computers spread over a wide geographical region.
What do routers do(simply), and why are they used?
relay information from on communication channel to another.
Used because its impractical to connect every network with all the other networks.
What are hosts?
computer’s that run applications.
What happens at the router when data is sent?
The data gets split up into packets, these get given a source address and destination address and get sent independently through a gateway for transmission to other routers which decide where to next send it by looking at the destination address and routing tables.
What is a IP address?
a unique address that identifies a computer or device on a network.
how many different address does IP’s IPv4 address allow?
2^32
What two parts is Ipv4 address split into?
The first 2 bytes are for the network id
The next 2 are for the host id.
What is replacing ipv4 and why?
Ipv6 with 2^128 address as ipv4 hasn’t got enough unique address anymore.
What does NAT stand for?
network address translation.
What is the world wide web?
a system of interlinked hypertext documents accessed via the internet.Part of the application layer, and uses HTTP/HTTPS as the application layer protocol
What is a Intranet?
A private network of computers used to share information or operations within an organisation.
still using IP/TCP
What is a domain name?
A name that identifies one or more ip addresses, eg google.co.uk
What is the proper name for a domain name such as www.google.co.uk ?
A fully qualified domain name. consists of a host ID and domain name.
includes all the domains so it can identify a specific host.
Who are domain names allocated by?
Internet Registrars
Who are private companies.
What are 3 top level domains?
.uk , .gov , .com
What is a second level domain?
.ac , .sch
What is a third level domain?
.hrsfc (one for hills)
What is the subdomain?
www.
What are DNS servers and what do they do?
They are a server that translates FQDM’s into IP addresses when a user makes a request in a browser.
(DNS request–> DNS servers—>ip back)
What does URL stand for?
Uniform resource locator.
What is URL?
A a short string that identifies a resource by its network location
What is the path of a URL?
the bit after the /
What is URI?
uniform resource identifier -includes URL’s and URNs ( uniform resources names) which identify resources by name.
What is a root?
the very last bit of a FQDM eq .uk
what are internet registries?
they store information on registered domain names, each major domain has its one registry.
What is a ISP?
internet service provider (or IAP-internet access provider) a organisation that sells people internet access
What is a server?
a software process that provides a service requested by a client.
What is a client?
A software process that requests and uses the services provided by a server.
what is the client-server model?
A client software process initiates a request for a service from a server software process, and the server responds to the request.
WHat is a protocol?
A set of agreed signals, codes and rules for data exchange between systems.
what is a protocol stack?
A collection of protocol layers, each layer is responsible for part of the process governed by the stack.
what is the TCP/IP protocol stack?
A protocol stack for the TCP/IP, it has a application layer, transport layer, network layer, and a link layer.
what is a port?
an address for a software process.
what is a socket?
A combination of a host ip address and a port number.
what is bidirectional?
data passes both ways at the same time.
How does the transport layer work?
Establishes end to end connections, ensures the whole message is sent, Numbers the packets in order, Splits the data into packets, asks for re-transmission if the data sent was incomplete. uses TCP to create reliable flow. MAkes sure port numbers are know.
how does the network layer work?
The network layer (IP layer) addresses the packets handed to it by the transport layer and labels them with a source , and destination IP address.
Is responsible for the routing across networks.
Each router sends packets to the next router, by using router tables and destination IP.
It also receives packets from the link layer, removes the source and destination and hands it to the transport layer,
how does the application layer work?
It handles the details of the particular networking application . Eg it uses HTTP for web browsers. ANd FTP for file transfer.(application specific protocols)
Interacts with the user application, data encoding and encryption.
how does the link layer work?
what does it interface with?
Interacts with the hardware.
Adds mac address
transports data across a network.
Address a source and destination HARDWARE address to received packets (from IP layer)
The destination address is the gateways hardware address.
Handles the physical details of interfacing with the cable, network interface card and a device driver.
What is the complete pactet structure prodced by the tcp/ip stack?
Data, then TCp’s source port, destination port and packet sequence, then Destination and source IP address, then LInks Source and gateway MAC address.
What are client port numbers?
A temporary port assigned when a client does a process. Allocated sequentially in the range 1024-4095
What are well know port numbers?
TCP needs to know what port the server will be using so they are well known port numbers in the range 0-1023.
What is the port number for HTTP?
80
What are the port numbers for FTP
20(data) and 21(command)
What is circuit switching?(shitty old not used anymore)
physical connection is established for the duration of the exchange
slow to establish
circuits are then unavailable for everyone else.
Whta is packet switching?
data is split into packets , which get transported seperetly . Each packet contains addressing info.
Paths can be shared wit other data
What is datagram packet switching?
Where each packet is routed independently using the most efficient route.
they may go different routes and arrive out of sequence -(so is reassembled)
this increases efficiency as route is decided as it being transmitted.
Unreliable- not guaranteed delivery
And packets have to carry lots of header info.
Used by IP
What does HTTP stand for?
Hypertext transfer protocol
What does FTP stand for?
File transfer protocol
What does a browser do?
accepts a URI from a user
Extracts the FQDM and sends a DNS request for its IP address.
Sends a GET request to the server host at port 80.
IT receives the returned file.
It renders the files contents .
If it contains other elements, eg pic- issue more GET requests.
What is telnet?
a text based protocol used to manage a remote machine.
Telnet port?
23
What is HTTPS
hypertext transfer protocol over secure sockets layer.
The data in and out is encrypted , used in online banking transactions.
Port for HTTPS?
443
two similarities between internet and intranet?
both use TCP/IP
Each have a agrees set of protocols to allow communication.
3 mail protocols
SMTP;
POP(3);
IMAP(4)
