Networks Flashcards

1
Q

Describe client-server networking

A

Most computers are nominated as clients and one or more as servers. The clients request services from the servers.

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2
Q

name an advantage of client-server networking

A

-Efficient allocation of resources

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3
Q

Name a disadvantage of client-server networking

A

-A single server is a point of failure

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4
Q

What is included in a network access device (router/gateway)?

A
  • WAP (wireless access point)
  • Switch
  • Router
  • Modem (sometimes)
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5
Q

What is a WAN?

A

A WAN (Wide Area Network) is a telecommunications network that extends over a large geographic area for the primary purpose of computer networking.

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6
Q

Why are WANs no longer used?

A

Companies use VPNs and connect over the internet because it is cheaper.

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7
Q

What is data sent through the internet in?

A

Packets

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8
Q

What is connectionless communication?

A

Connectionless communication is a data transmission method used in packet switching networks in which each data unit is individually addressed and routed based on information carried in each unit.

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9
Q

Which packets are directed to the WAN interface and which are directed to the LAN interface?

A

All packets that are not for the local network are directed to the WAN interface.

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10
Q

How does the router decide on where to send a packet?

A

It uses a routing table to determine the best next hop for the packet.

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11
Q

What happens if part of the communications infrastructure fails?

A

The router chooses a different route and subsequent packets may be sent over a different path.

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12
Q

What happens if the router is too busy?

A

The packets are buffered in memory, causing high latency.

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13
Q

What happens if a router runs out of memory?

A

The incoming packets are discarded and they will need to be resent.

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14
Q

What happens if a packet contains a ToS (Type of Service) field in the packet header?

A

The packet is placed at a higher priority level and gets placed at the front of the queue of packets to be routed.

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15
Q

What is a TTL?

A

A TTL (Time to Live) determines how long a packet could loop between routers before being discarded.

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16
Q

What are the components of a packet?

A

Packets contain:

  • Sender’s IP address
  • Recipient’s IP address
  • Protocol used
  • Packet sequence number
  • Payload (the data)
  • Checksum
17
Q

What is a router?

A

A router is a networking device that forwards data packets between computer networks.

18
Q

What is a gateway?

A

A gateway is a hardware device that acts as a “gate” between two networks. This can be a router, firewall or server.

19
Q

How is routing achieved?

A

The router receives a packet, the router calculates the optimal hop to the next router, then the packet is sent to that router.

20
Q

How can a firewall be implemented?

A

A firewall can be implemented in hardware, software or a combination of both.

21
Q

How does static filtering work?

A

A firewall will check the headers of packets against a set of rules or ‘packet filters’ defined by the network administrator.

22
Q

What does the packet header field include?

A
  • Source IP address
  • Destination IP address
  • Port number
  • Protocol
23
Q

Give an example of a commonly blocked protocol

A

SSH (secure shell) headers are typically blocked as they are used to remotely manage computers.

24
Q

How does stateful inspection work?

A

Stateful inspection continuously monitors incoming and outgoing traffic after a connection is established, analysing packet types and looking inside the payload of the packet as well as the header.

25
Q

How does a proxy server work?

A

A proxy server sits between the client devices and the firewall. It can also keep a cache of websites, serving them from its cache wherever possible, which speeds up user access and reduces network traffic.

26
Q

Where are proxy servers commonly used?

A

Networks within schools often use a proxy server as a method of filtering websites for safeguarding purposes, so that young people do not inadvertently see material that is inappropriate.

27
Q

How are IP addresses written?

A

IP addresses are written in dotted decimal notation, where the four denary values are then written with a dot between them. (120.16.130.210) The first part of an IP address is the network ID, the second part is the host ID.

28
Q

What are subnet masks used for?

A

Subnet masks contain 1s in the position of the network ID and 0s in the position of the host ID.

29
Q

What does DHCP stand for?

A

Dynamic Host Configuration Protocol

30
Q

What does DHCP do?

A

DHCP dynamically assigns private (non routable) IP addresses and other configuration options to devices on a network.

31
Q

How does DHCP use DORA to allocate IP addresses?

A

DORA is a 4 step procedure (Discovery, offer, request, acknowledgement) which allocates IP addresses to each system in a network.

32
Q

What does NAT stand for?

A

Network Address Translation

33
Q

What does NAT do?

A

A NAT address enables private IP networks that use unregistered IP addresses to connect to the Internet.

34
Q

What is port forwarding?

A

Port forwarding allows remote computers (i.e. computers on the internet) to connect to a specific computer, or service within a private local area network.

35
Q

What does port forwarding do?

A

The network access device can be configured so that any traffic that arrives on port 80 is forwarded to a specific internal IP address

36
Q

What is CRUD an acronym for?

A

Create, Retrieve, Update, Delete

37
Q

What does REST do?

A
REST enables CRUD to be mapped to database functions for example:
• GET → SELECT
• POST → INSERT
• DELETE → DELETE
• PUT → UPDATE.
38
Q

Compare JSON with XML

A

JSON is:

  • Easier for humans to read
  • More compact
  • Easier to create
  • Easier for computers to parse