3b. Networks and Communications Flashcards
What is a switch?
A device that connects several devices together to enable communication to take place. You can do things such as limit the bandwidth on certain ports.
What is a master switch also called?
Backbone switch.
What is a hub?
A hub looks the same as a switch. It is very similar but the data that goes through it isn’t filtered. Data is also more susceptible to interception. Collisions can also occur.
What is a WAP?
Wireless access point. A hub that communicates by wireless instead of having physical connections.
What is a NIC?
Network interface card. Enable a computer to be connected to a network using a cable. More modern computers have these built in on the motherboard. Each NIC has a MAC so that each card is unique.
What does MAC stand for?
Media access control.
What is a wireless network interface card?
To connect to a WAP, a device needs a wireless NIC.
What is a router?
An advanced version of a switch. Mainly used to connect a LAN to a WAN. Were once used only by big companies, now a household item.
What is a repeater?
Signals deteriorate after long cables, so a device is required to extend the range.
What is a bridge?
Used to connect two LANs together. It’s similar to a router but it does not store the addresses of devices connected to it.
What is a server?
A powerful computer that performs functions on behalf of clients connected to it. There are many different types of server and the size an functionality of a network will dictate how many are needed.
What is a file server?
A file server stores files available on the network. It will normally have storage areas set aside for each user on the network that are only accessible to those users.
What is an application server?
An application server stores software for use across the network. The application can either be run from the server by a client computer, or the software installation files can be stored on the server so they can be deployed to client computers.
What is a disadvantage of an application server?
A lot of network traffic if run from the server. If the installation files are taken from there it requires the clients computer to have the right processor, memory, etc.
What is a mail server?
Receives all incoming emails and then allocates them to the appropriate inbox. If the user sends an email it goes to the server and then to somebody else on the LAN/WAN or to the internet. It also filters out spam.
What is a proxy server?
Maintain access to the internet within an organisation. Can store cache so websites are quicker to load for other clients. A firewall. Filter access to webpages, so some are blocked.
What is a print server?
Manages access to printers within the LAN. Reduces the processing burden on client computers. All print jobs will go in a queue. Can prioritise some in the queue. Can provide reports of who has printed what.
What is a back up server?
Backs up all data on a network so that individual users do not have to do it. Usually connected to tape drives. Back up jobs will be scheduled so that they run automatically every day, usually over night.
Name 4 types of optical communication methods.
Infrared, fibre, optic and laser.
What is infrared?
Only works at short distances, no more than 10 metres. Requires direct line of sight. Bandwidth is restricted to 115.2kbpd.
What uses infrared?
Remote controls. Used to be main wireless communication before bluetooth (for phones, laptops, etc.)
Describe fibre optics.
Data travels at the speed of light. Used in LANs where distances of more than 100 metres need to be covered. Virgin Media use fibre optics to broadcast cable television signals and to provide broadband.
What is laser communication?
Two laser devices in direct line of sight to each other. Each sends and receives a laser beam. Travels at speed of light. Only works in line of sight. Used in laser tag.
Name 2 wireless communication devices.
Bluetooth and radio.
What is bluetooth?
Range of 10m. Can get applications such as bluetooth headsets for phones, replaced infrared.
Advantages of bluetooth?
Widely available, a radio frequency licence is not required, it does not require line of sight, a pass key can be used to prevent non authorised devices from connectong.
Disadvantages of bluetooth?
10m range. Can only connect to one device at once.
What is radio?
Wi fi. Used to connect to LAN or WANs. Can connect printers via wi fi.
Advantages of radio/wi fi?
No need to connect devices using cables, portable devices are not restricted to a particular location for network access, line of sight isn’t required, wi fi standards globally
Disadvantages of radio/wi fi?
The range is 30 metres but can be further restricted by walls and steel construction, bandwidth is shared, wireless networks are susceptible to hacking.
What is a fax machine?
A 2d document can be fed through the fax and sent electronically via a telephone line to another fax which will print it. Confidentially not safe as anyone could pick it up at other side.
Advantages of email:
Send messages to multiple people at once, send attachments, secure due to login required, filter out junk email.
What is a bulletin board?
Discuss topics with people (business or pleasure) The discussion board is the whole website, forums are the subjects of discussion and threads are the topics of the discussion. You can subscribe to threads/forums and some users will have public profiles.
What is tele/video conferencing?
Allows you to speak to large groups of people. Good for meetings. Can share documents.
What is Internet Relay Chat? (IRC)
Sharing ideas with colleagues/social communication. Like Facebook chat. Keeps logs of conversations. The use of emoticons. Multiple people in conversation.
