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Paper 2 - Computer Science > The Internet > Flashcards

Flashcards in The Internet Deck (18)
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1

What is an ISP?

An internet service provider is a company that provides customers with access to the Internet.

2

What do National ISP's provide?

National internet service providers provide internet access to smaller regional ISPs

3

What is a packet switched network?

- A network in which data is sent in packets.
-Data is split into multiple packets, each of which is sent to its recipient via the best possible route before being reassembled with other packets by its recipient.

4

What happens when a packet is sent through a network?

- It passes through a number of routers before reaching its destination.
- A router uses the recipient address on a packet to determine where to send the packet.

5

What is the definition of a hop?

- A hop occurs every time that a packet passes through a router.
- Packets have finite numbers of hops

6

What is a packets TTL?

A packet's time to live is the number of hops the packet can partake in before it's dropped.

7

What happens when a packet's TTL expires

The packet is said to be dropped. The recipient will notice a missing packet and request for it to be sent again

8

What are the components of a data packet?

- Sender’s address
- Receiver's address
- Packet contents (known as the payload)
- Time to live
- Sequence number
(some packets have a checksum in their trailer)

9

What does URL stand for and what are they used for?

- A uniform resource locator is the full address for an internet resource
-It's what typed into the search bar

10

What does TLD stand for? Give some examples

Stands for Top level domains : .com .net .org .uk

11

What are domain names and why are they used?

- A domain name identifies a website on the Internet.
- IP addresses are hard to remember, so domain names map to IP addresses
- Domain names use alphanumeric characters so are easier for humans to remember.

12

What does FQDN stand for and what is it?

-A fully qualified domain name specifies an exact resource on the internet.
-It must include the host server name (www/mail/ftp)

13

What do domain name servers do?

- When you enter a domain name into your browser’s address bar, a domain name server is used to translate the domain name into its corresponding IP address.

14

How do domain name servers store domain names?

They store a table of domain names and their corresponding IP address.

15

What happens if a domain name server does not have a record of the domain that you want to access?

The request is passed to another larger domain name server.

16

What is an internet registry and what do they do?

- An internet registry is an organisation allocates of IP addresses.
- They protect the depleting pool of unallocated IP addresses.
-They check for previously allocated, now unused IP addresses before allocating a brand new one.

17

What ia an internet registrar?

-They ensure domain names are only used by one organisation.
-They hold records of all the existing domain names

18

What route do data packets take?

The fastest or least congested route