Networks, topologies and protocols

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レッスンノートスライド練習問題

レッスンノート

Types of network

LAN (local area network): covers a small area (building); owned by the organisation. WAN (wide area network): covers a large area (the Internet is the largest WAN); uses third-party links.
Client-server: a central server provides services (files, web, email) to clients; easier to manage and secure. Peer-to-peer: each computer shares resources equally; cheap, but harder to manage and less secure.

A home local-area network

Hardware

NIC (network interface card), router (connects networks and directs data), switch (connects devices in a LAN), wireless access point (WAP), modem, cables (copper, fibre optic) or wireless.

A central switch in a star LAN

Topologies

Star: all devices connect to a central switch; if one cable fails, others work; the switch is a single point of failure; popular.
Mesh: devices connect to many others; very reliable but costly.

Addresses

An IP address identifies a network interface for routing and communication; IPv6 offers a much larger address space than IPv4.
A MAC address identifies an interface on a local link. It may be manufacturer-assigned or locally assigned/randomised; it is not an infallible permanent identity.
DNS resolves domain names to associated records, including IP addresses.

Protocols and layers

A protocol defines communication rules. HTTP/HTTPS serve the Web, SMTP sends email, IMAP/POP access mail, and FTP is specifically named for file transfer. HTTP can transfer files too.
HTTPS uses TLS to protect HTTP traffic in transit and authenticate the server; it does not guarantee that a site’s contents are trustworthy.
IP forwards packets between networks. TCP can provide ordered reliable delivery, including recovery of missing data; not every protocol retransmits packets.

Client requests and server responses

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練習問題

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1.What does LAN stand for?
Easy
- Alocal area network
- Blarge area network
- Clong access network
- Dlinked area node
2.What does WAN stand for?
Easy
- Awide area network
- Bweb area network
- Cwired area network
- Dwireless area node
3.What is a router?
Easy
- Aa device that connects networks and directs data
- Ba storage device
- Ca printer
- Da monitor
4.What is a switch?
Easy
- Aconnects devices in a LAN
- Bconnects networks
- Cstores data
- Dencrypts data
5.What is an IP address?
Easy
- Aidentifies a device on a network
- Ba hardware ID
- Ca website name
- Da password
6.What is a MAC address?
Easy
- Aan address identifying a network interface on a local link
- Ba website domain name
- Can email message
- Da password
7.What is a protocol?
Easy
- Aa set of rules for communication
- Ba type of cable
- Ca device
- Da program
8.Which protocol is used to send email?
Easy
- ASMTP
- BHTTP
- CFTP
- DIMAP

もっと問題

9.Which protocol’s name specifically means File Transfer Protocol?
Easy
- AFTP
- BSMTP
- CHTTP
- DDNS
10.What is a client?
Easy
- Aa device that requests services from a server
- Bthe central computer
- Ca router
- Da cable
11.What is a server?
Easy
- Aa computer that provides services to clients
- Ba user
- Ca router
- Da cable
12.Which topology uses a central switch?
Medium
- Astar
- Bmesh
- Cnone
- Dring only
13.In a switched star LAN without redundant end-device links, what is a benefit?
Medium
- Afailure of one end-device cable normally affects only that device
- Bno central device is needed
- Cit is always the cheapest topology
- Dit requires no communication links
14.What is a disadvantage of a star network?
Medium
- Athe switch is a single point of failure
- Bone cable breaks all
- Cit is slow
- Dit needs no switches
15.What is an advantage of a mesh network?
Medium
- Avery reliable as there are several paths
- Bcheap
- Csimple
- Dcentral control
16.What is a disadvantage of a fully connected wired mesh?
Medium
- Aexpensive and complex to set up
- Bone failure breaks all
- Cpoor reliability
- Dslow
17.Which is a benefit of client-server over peer-to-peer?
Medium
- Aeasier to manage and secure
- Bcheaper
- Cno server needed
- Deveryone equal
18.What are packets?
Medium
- Asmall chunks of data sent across a network
- Btypes of cable
- Cfiles
- Dprotocols
19.Why are data sent in packets?
Medium
- Apackets can take different routes and be resent if lost
- Bto make data bigger
- Cto slow data
- Dto delete data
20.What does HTTPS add to HTTP?
Medium
- Aencryption
- Bspeed
- Cstorage
- Dcolour
21.Which device would a home use to connect to the Internet and direct data?
Medium
- Aa router
- Ba printer
- Ca scanner
- Da keyboard
22.Why can IPv6 replace IPv4?
Medium
- Athere are not enough IPv4 addresses
- BIPv6 is shorter
- CIPv4 is secure
- DIPv6 is slower
23.What is the Internet?
Easy
- Aa worldwide network of networks
- Ba single website
- Ca type of cable
- Da program
24.What is the web?
Easy
- Awebsites accessed via the Internet
- Bthe Internet itself
- Ca router
- Da network
25.What is a wireless access point (WAP)?
Medium
- Aa device that lets wireless devices join a network
- Ba cable
- Ca printer
- Da firewall
26.What is bandwidth?
Medium
- Athe amount of data that can be transferred per second
- Bstorage
- Cscreen size
- DCPU speed
27.The Internet is a WAN.
Easy
True or false?
28.DNS converts domain names to IP addresses.
Easy
True or false?
29.Every network interface must change its MAC address once per day.
Easy
True or false?
30.In the switched star LAN described here, devices connect to a central switch.
Easy
True or false?
31.Peer-to-peer networks always need a server.
Medium
True or false?
32.Which are network devices?
Medium
- Arouter
- Bswitch
- CNIC
- DWAP
- EROM
33.Which are protocols?
Medium
- AHTTP
- BFTP
- CSMTP
- DIMAP
- ERAM
34.Explain two advantages of a star topology.
Medium

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