9.2 Networking Flashcards
Define network topology?
Refers to the structure of the network and are 2 types: physical and logical.
what is a physical network topology?
refers to the actual architecture of a network. Networks using a physical topology will interconnect components differently to those networks that use another physical topology. There are to types: star and bus.
How does physical network topology work?
Each client has its own connection the central hub.
What are the disadvantages and advantages of physical star network topology?
(A) Data is sent directly to its recipient, over a cable that is connected only to the recipient. Other clients on the network cannot see data that isn’t intended for them.
(A) It is easy to add and remove clients from the network.
(A) The failure of one cable does not affect the performance of the rest of the network.
(D) If the central hub fails all communication over the network is stopped.
(D) It is expensive to install due to the amount of cables.
How does a physical bus topology work?
Connects clients to a single cable called a backbone. there is no need for a central hub.
What are the advantages and disadvantages of physical bus topology?
(A) there is not central hub reducing the chances of network failure
(A) Inexpensive to install as no need for a hub and low amount of cables
(D) Data is sent through a shared backbone allowing every client on the network to see data that isn’t intended for them.
(D) The backbone has multiple clients which introduces the risk of collisions.
(D) if the backbone fails the entire network becomes unusable.
What is a logical network topology?
Refers to the flow of data packets within a network. A logical bus network delivers packets to all clients but a logical star network defilers packets only to the recipient.
Why are topologies usually mixed?
If a network is set up as physical star it can still behave as a logical bus. Running special software on the hub allows it to distribute data to all of the connected clients so it acts like a bus network
What is a host in networks?
A device on a network that provides services. This is often a server, which can provide services such as file storage but can also be the clients on a network themselves.
How does client-server networking work?
A central server provides services to the clients on the network. Servers are connected to the network in the same way as clients but are often more powerful than the clients.
What are the advantages and disadvantages of client-server networking?
It can improve security but requires high level of expertise to set up and manage.
How does peer-to-peer networking work?
Services are provided by the clients themselves.
What are the advantages and disadvantages of peer-to-peer networking?
(D) All of the clients which provide the services must be running in order for the network to be operational. If the computer that manages storage is off none of the clients on the network can access their files.
(A) It is more cost effective than client-server as there is not need for a powerful server to provide services.
(A) they are easier to set up and maintain.
What’s the main benefit of wireless networking?
It allows clients to communicate within a network without being physically connected to it.
How do wireless networks work?
They require a wireless access point, which connects to a wired network just like any other client would, and a wireless network adapter in the device that connects to the wireless network.
What is WIFI?
A wireless local area network that is based on international standards. It allows a device made in one part of the world to connect seamlessly to wireless networks all over the world
What are the 3 ways of keeping WiFi secure?
Encrypting transmitted data, disabling SSID and setting up a MAC address filter
How can you encrypt transmitted data on a wireless network and how can it keep the network secure?
By encrypting transmitted data using WPA or WPA2. WPA stands for WiFi protected access and requires that a new wireless client enters a password in order to connect to the network.
How can disabling SSID broadcast keep a wireless network secure?
SSID stands for service set identifier and is the name that identifies a wireless network. Disabling SSID broadcast stops wireless devices within range of the network from displaying that the network is available, only allowing those who know the SSID to connect.
How can setting up MAC address filtering keep a wireless network secure?
MAC (media access control) addresses are assigned to every wireless device by their manufacturer and are unique to that device. MAC address whitelist can be created to allow only specific devices to connect to a network. Likewise MAC address blacklists can be used to block specific devices from connecting to a network.
What does CSMA/CA stand for?
Carrier sense multiple access with collision avoidance.
What is CSMA/CA?
A protocol used in wireless networks to avoid data collisions caused by multiple devices communicating simultaneously.
How does the CSMA/CA protocol work?
When a device is ready to transmit, it listens to its communication channel to check whether it is idle. If so then the data is transmitted. If the channel is busy the device waits for a random period of time before checking the channel again. An exponential algorithm can be used to increase the time period for which the device waits with each check of the channel.
What is the main drawback to the CSMA/CA protocol?
Hidden nodes: when the device checking for an idle channel cannot “see” some parts of the network on which communication may be occurring.
How do you get around the hidden nodes problem in the CSMA/CA protocol?
A protocol called request to send/clear to send (RTS/CTS) is used.
How does the request to send / clear to send (RTS/CTS) protocol work?
By adding an additional step into the CSMA process. Once the channel is checked to be idle the transmitting device will send a “request to send” message to the server. If the server is indeed idle it will respond with a “clear to send” message at which point the transmitting device can begin to communicate with the server. If no “clear to send” message is received the server is busy communicating with a hidden node and the transmitting device must wait before starting the CSMA process again.
