N3. TCP client-server

Question 1

What is a server?

Answer 1

A host/program that provides a service:

• waits for clients to connect
• application-specific service

Question 2

What is a client?

Answer 2

A program that makes use of a service:

• must identify a server and connect to it
• typically has interface for a human user e.g. GUI

Question 3

What is a FQDN?

Answer 3

Fully Qualified Domain Name
e.g. www.cs.st-andrews.ac.uk
complete domain name for a specific computer or host on the internet - specifies location in DNS.

Question 4

What is an IPv4 address?

Answer 4

Unique address/number in a network for a specific computer/host.
Uses dotted decimal notation
e.g. 138.251.10.53

Question 5

What is DNS?

Answer 5

Domain Name System.
Mapping of FQDN to address.
(or address lookup from IP address to FQDN)

Question 6

Properties of TCP port numbers

Answer 6

• layer 4 de-multiplexers
• assigned - “well known”
• ephemeral, dynamic - allocated by OS
  (port is a localised address for a machine)