5 - 21 Structure of the Internet Flashcards
Briefly describe the physical structure of the internet
Each continent uses backbone cables connected by trans-continental leased lines fed across the sea beds. National Internet Service Providers (ISPs) connect directly to this backbone and distribute the Internet connection to smaller providers who in turn provide access to individual homes and businesses.
Describe a URL
A Uniform Resource Locator (URL) is the full address of an internet resource. It specifies the location of a resource on the internet, including the resource name and usually the file type, so that a browser can request it from the website server.
What are Internet registrars?
Internet registrars hold records of all existing website names and details of those domains that are currently available to purchase. These are companies that act as re sellers for domain name and allow people and companies to purchase them. All registrars must be accredited by their governing registry.
What are Internet registries?
Internet registries are five global organisations governed by the Internet Corporation for Assigned Names and Numbers (ICANN) with worldwide databases that hold records of all the domain names currently issued to individuals and companies, and their details.
What is a domain name and a DNS
A domain name identifies the area or domain that an internet resource resides in. These are structures into hierarchy of smaller domains and written as a string separated by full stops as dictated by the rules of the Domain Name System (DNS).
What is a Fully Qualified Domain Name?
A Fully Qualified Domain Name (FQDN) is one that includes the host server name, e.g. www, mail or ftp depending on whether the resource being requested is hosted on the web, mail or ftp server. This would be written as www.websitename.co.uk or mail.websitename.co.uk for example.
What is an IP address?
An IP or and IP address is a unique address that is assigned to a network device.
What is an IP used for?
An IP address indicated where a packet of data is to be sent from. Routers can use this address to direct the data packet accordingly. If a domain name is associated with a specific IP address, the IP address is the address of the server that the website resides on.
What are the advantages and disadvantages of a bus topology?
+ Inexpensive to install - less cable than star topology and no additional hardware
- If the main cable fails, network data can no longer be transmitted to the nodes
- Performance degrades with heavy traffic
- Low security - all computers on the network can see all data transmissions
Describe the physical apperance of a typical bus topology
All computers are connected to a single cable. The ends of the cable are plugged into a terminator.
What are the advantages and disadvantages of a bus topology?
+ Inexpensive to install - less cable than star topology and no additional hardware
- If the main cable fails, network data can no longer be transmitted to the nodes
- Performance degrades with heavy traffic
- Low security - all computers on the network can see all data transmissions
Describe the physical apperance of a typical star topology
A star network has a central node, which may be a switch or a computer which acts as router to transmit messages.
Describe the physical apperance of a typical star topology
A star network has a central node, which may be a switch or a computer which acts as router to transmit messages.
What are the advantages of a star topology?
+ If one cable fails only one station is affected making it easy to isolate faults.
+ Consistent performance
+ No problem with collisions of data since each cable has its own server
+ the system is more secure as messages are sent directly to the central computer
+ Easy to add new stations without disrupting the network
What are the disadvantages of a star topology?
- May be costly to install because of length of cable required
- If the central device goes down, network data can no longer be transmitted to any of the nodes.
