Unit 5 Flashcards
(41 cards)
How does World Wide Web works?
- Client enter web address (URL),either a web page or an individual file, in the web browser.
2.DNS server resolves the URL(Domain name) to corresponding IPA.
3.Web browser connects to the web server using IPA and requests a relevant webpage/file.(HTTP)
4.Webpage is transferred from one computer to another using HTTP/S.
5.Web server sends data to Web Browser in HTML format and Web Browser displays web page as described in HTML, in readable format
How are data sent across the networks?
1.The sending computer splits the data into packets.
2.Each packet has packet header containing (Sender’s address, Destination address, Current packet number, Total number of packets that make up the data)
3.Each packet is sent to ISP.
4.The router of ISP lookup the packet header and forward the packets to its destination.(most efficient path)
5.Packets take different routes across the network.(not arrive in order)
6.Receiving computer reassemble the data in correct order using Information in header.
By Internet Protocol in network layer
IPv4 Format and Bit
•Numeric Dotted-Decimal Notation
•32 bits
•4 groups of 8 bit number(Octets)
•Eg. 192.0.12.246
IPv6 Format and Bits
•Aphanumeric colon Hexadecimal Notation
•128 bits
•8 groups of 4 Hexadecimal (Each hexa->4bits)
Component Needed to Access the internet.
Internet->Modem->Router->Switch->Workstations
Wireless Access Point(WAP)
•Allow wireless devices to connect wired connection using Wi-Fi.
•Convert Data to wireless signal and Vice Versa.
-Transmit to all devices(Like Hub)
Router
•Networking Hardware that forward packet to the destination between networks(Not only one like switch)
•Both cable and wifi connection
Modem
Covert the signals in a LAN into signals that can be transmitted along the cables provided by ISP.(Access to Internet)
WWW vs Internet
Internet is a wide area network spanning across the globe.
WWW is a service provided by Internet that provides access to web pages.
Web Browser Job?
It converts data received from the web server to human readable format.
Differences between email protocols?
SMTP: Sending Emails over the internet. Set Format of msgs, what commands for email servers to understand, how they should respond.
POP3: Connect to mail servers and retrieving, downloading ,deleting Emails
IMAP: Allow access from multiple email clients
TCP vs UDP?
TCP sends acknowledgement when data is received correctly.
UDP(User Datagram Protocol) doesn’t check when received.
Used when Speed is more desirable.(Live Broadcast)
What is a server?
Powerful computer that provides the network with services such as storing files and sending/receiving emails
Process of client access to data.
•Client make a connection with server using its address
•Once connection is made, Client make service request.
•If request valid, server sends requested data using client’s address.
Peer to Peer networks’ advantage.
No records->No privacy concerns
(Used to share pirated movies)
Types of network topologies?
•Bus: Single cable to which each device is connected.(terminator at each end)
•Ring: Cable connects devices in a closed loop.(Travel same direction). Data is passed from device to next until reaches its destination.
•Star: Each device connected to a central network device(Hub/Switch)
•Mesh: Every devices is connected to every devices
Purpose of terminator in a bus topology?
-To absorb the signals that have reached the end of the cable.
-Prevents them from bouncing back and causing interference.
When does collision occurs in bus?
When two or more devices send a message at the same time, making them unreadable.
What is CSMA/CD and function?
•Carrier Sense Multiple Access/Collision Detection.
•Deal with multiple messages at the same time in bus where only one message can be sent at the same time.
Algorithm of CSMA/CD?
- Check if bus is busy
- If not busy->Send msg&Go 1
- Listen if msg received correctly
- If not received correctly, go 5, else go back to listening for msgs
- Wait->Go 1 to retry sending msg
Pros and cons of Bus Topology
Pros
•Cheaper->Single cable
•Easy add extra network devicea
Cons
•Only 1 msg at a time-> Slower as more Network devices
•If cable damage, whole network fails
•Diffcult to identify fault
•All data sent is received by all devices->Security risk
Pros and cons of Ring?
Pros
•Adding extra device doesn’t affect performance
•Easy to add extra device
Cons
•Need whole network shut down when add/remove device
•If cable damage, whole network fails.
•Difficult to identify fault
•More expensive to install than bus(More cable)
Pros and cons of Star
Pros
•Easy to locate fault
•Add/remove device w/I shutting down
•Damaged cable->Don’t stop the network;only connected device
•If Switch-> Efficient (messages only send to intended devices)
[More security, other can’t see]
Cons
•Whole network fail when hub/switch damage
•Expensive to install (More cable and hub/switch)
Pros and cons of Mesh
Pros
•Very Fault tolerant as message can be rerouted if one device fail
•High performance (Each node connected to multiple devices)
•Wireless->Each node extends the range
Cons
•Difficult to manage (Due its number of connections)
•Expensive to install wired mash networks