Unit 5 - Networks and webtechnologies Flashcards
URL
Is the full address of an internet resource. It specifies the location of a resource on the Internet, including the resource name usually the file type so that a browser can request it from a website server.
Registers
Hold records of all existing website names and the details of those domains that are currently available to purchase.
DNS
A domain name identifies the area or domain that an internet resource resides in. These are structured into a hierarchy of smaller domains and written as a string separated by full stops as dictated by the rules of the DNS
IP address
An IP or internet protocol is a unique address that is assigned to a network device
WAN
As a network of interconnected networks, the internet comprises millions if not billions of local area networks and individual users to form the world’s largest WAN.
LAN
Consists of a number of computing devices on a single site or in a single building, connected together by cables
Physical bus
Can use different layouts or topologies. In a bus topology, all computers are connected to a single cable.
Advantages / Disadvantages of bus topology
The advantage to installing as it requires less cable to install
Disadvantage: If the main cable fails, network data can no longer be transmitted to any of the nodes.
Performance degrades with heavy traffic
Low security
Physical start topology.
A central node acts as a router and has multiple computers linked to it.
Advantages/disadvantages of star topology
Advantages:
If one cable falls one station is affected only
Consistent performance
Higher transmission speeds can give better performance than a bus network
No problems with “collisions” of data since each station has it’s own cable to the server
The system is more secure as are sent directly to the central computer cannot be intercepted by other stations.
Easy to add new stations.
Disadvantages:
It May be costly to install because of the length of cable required
If the central system goes down the whole thing goes to shit.
Wi-Fi
Local area wireless technology that enables you to connect a device such as a PC, smartphone, laptop to a network resource / the internet
WAP
Wireless network adapter. All stations share a single radio frequency communication channel. Transmissions are received by all stations within the WAP. To connect to the Internet the WAP usually connects to a router.
Mesh Network topologies.
Only one node requires a connection to the internet and all the others can share the connection.
Advantages of mesh networking:
No cable costs
More nodes = more reliable.
New nodes are automatically incorporated into the network.
Faster communication since data packs do not need to travel via central switch
Circuit switching
Circuit switching is a connection-oriented network switching technique. Here, a dedicated route is established between the source and the destination and the entire message is transferred through it.
ADV- Fixed data transfer rate and fixed bandwidth.
Increased quality of communication.
DIS-Channel resources not used fully, long time to establish connection, Requires more bandwidth.
Packet switching
Packet switching is the transfer of small pieces of data across various networks. It is important as these data chunks or “packets” allow for faster, more efficient data transfer as bigger files can be broken down into smaller packets of 512 bytes. Every packet is given its own distinct address.
Gateways
A gateway is used to translate between protocols.
MAC
Unique address written on a piece of hardware.
Importance of protocols
A protocol is a set of rules defining common methods of data communication. These rules need to be standard across all devices in order for them to communicate with each other.
What is the TCP - IP protocol (include packet switching)
TCP - IP (Transmission Control Protocol - Internet Protocol) is the protocol for 2 computers to communicate with each other. When they do communicated data is sent in packets in the size of 512 bytes.
TCP-IP is a set of rules for communication over the internet.
The roles of the four layers:
Application layer: Sits at the top used to transmit data over a network, usually the internet.
Transport layer: Uses TCP to establish end to end connection with the recipient computer. Data is split into packets and labled with the packet number.If any packet is lost the trasnport layer requests retransmission of lost packets.
The internet layer: Adds the source and destination ip addresses.
The link layer: Physical connection between network nodes and MAC addresses indetifying the NICs.
Firewalls
A firewall is a security checkpoint between two networks. Can be implemented in both hardware and software. And it may act as a proxy server.
Proxy servers
A proxy server intercepts all packets entering and leaving a network - this enables privcay and anonymous surfing. A proxy can also maintain a cache of websited visited.
What are the advantages of having a CSS file outside of the HTML file instead of having it embedded? (treat this as a high band question)
External CSS files enable you to apply styles on a single CSS stylesheet to multiple HTML files throughout an entire website.
This also removes the CSS from the HTML pages, which makes them easier to read.
