Network Components

Question 1

What does DHCP stand for?

Answer 1

Dynamic Host Control Protocol - DHCP server automatically assigns IP addresses on a network.

Question 2

APIPA?

Answer 2

Automatic Private IP Addressing/Assigning - Windows feature that assigns one of a range of reserved IP’s to a windows device when a connection to a DHCP server cannot be established. This lets the device stay connected to local devices but not to the wider area network (WAN) e.g. the internet.

Question 3

DNS?

Answer 3

Domain Name SYSTEM - converts domain names like google.com to machine readable IP addresses. Phone book of the internet.

Question 4

PoE?

Answer 4

Power over Ethernet - physical/voltage power provided through ethernet cable.

Question 4

ECC?

Answer 4

Error Correcting Code - detects and corrects data bit corruption (one extra DIMM (dual inline memory module) to do the ECC on).

Question 4

SNR?

Answer 4

Signal to Noise Ratio - a measure of the interference level over a network.

Question 5

MAN?

Answer 5

Metropolitan Area Network (several buildings etc)

Question 6

PAN?

Answer 6

Personal Area Network (e.g. a Bluetooth network)

Question 7

What does a Load Balancer do in a network?

Answer 7

Distributes/spreads load over multiple servers to maintain speeds and uptime.

Question 8

What type of infrastructure network is SCADA used for?

Answer 8

Supervisory Control and Data Acquisition (SCADA)

Controlling infrastructure like power, machinery in a factory, etc. No access from outside.

An example of a Industrial Control System (ICS).

Closed Loop system

Question 9

What is a Tone Generator tool used for?

Answer 9

To find the corresponding end of a cable by making a noise when in contact with the device (Fox and Hound).

Question 10

SO/HO Router?

Answer 10

Small Office/Home Office Router (routes/directs data over a network)

Question 11

SSID in networking?

Answer 11

The customisable name of a wifi network.

Service Set IDentifier

Question 12

What is a Media Tester used for in networking?

Answer 12

A tool for testing that network cables are working.

Question 13

What is the 802.11 standard?

Answer 13

The most common wireless network standard with various types of sub standards.

Question 14

What does MU-MIMO stand for?

Answer 14

Multi-User-Multiple Input/Multiple Output - allows a single Access Point (AP like a Modem) to transmit data simultaneously to multiple devices. Provided by 802.11ax standard.

Question 15

What are the main transmitting frequencies used for wifi?

Answer 15

2.4GHz and 5GHz

Question 16

What is the rough maximum range of Bluetooth devices?

Answer 16

100m.

Question 17

What is a VLAN?

Answer 17

Virtual Local Area Network - devices on the network segregated virtually as opposed to using multiple routers and more cables.

Question 18

What is a Subnet?

Answer 18

Sub Network - A small network that makes up part of a larger network split off from it with routers.

Question 19

In the TCP three-way handshake (signal exchange) what does SYN and ACK stand for?

Answer 19

SYN - SYNchronise, a TCP data packet.
ACK - ACKnowledge, acknowledgement receipt.

The three TCP handshake steps:
1. Synchronize (SYN) - source PC sends a query to see if receiving device has any connections open/open ports.

2. Synchronize-acknowledge (SYN-ACK) - if the receiving computer (passive client) has open ports that can accept the connection, it sends back a synchronize-acknowledge (SYN-ACK) packet to the initiating computer.
3. Acknowledge (ACK) - the initiating computer (active client) then sends an acknowledge sequence number (ACK) packet back to the receiving computer, acknowledging receipt of the SYN-ACK packet. The data transmission/transfer can then begin.

Question 20

Does UDP (User Datagram Protocol) guarantee data is delivered like TCP does?

Answer 20

No. UDP just flings out data at a receiving device it DOESN’T establish a connection (connectionless) or guarantee data is received by the requesting device.

UDP is one way traffic. No connection/session is established.

Question 21

What does NAT stand for in networking?

Answer 21

Network Address Translation - a router service that translates a set of Private IP’s into Public IP’s and vice versa.

Question 22

What two protocols are used for RECEIVING emails?

Answer 22

IMAP4 and POP3.

Question 23

What does the ARP cache store?

Answer 23

The ARP cache stores a list of IP address and their MAC address counterparts to increase network speed (ARP checks through its list (cache) before searching further afield in the network for an address. It flushes/clears its cache of dynamic IP/MAC combos but keeps static IP/MAC address pairs permanently.

Question 24

Define topology.

Answer 24

How parts of a whole (constituent parts) are arranged/laid out. How components are laid out and connected. E.g. a network topology is how network devices are laid out and connected.

Question 25

What is the CMD prompt input/s for changing the devices' dynamic IP?

Answer 25

ipconfig/release - drops the current IP address ipconfig/renew - gets a new IP address from the DHCP server pool

Question 26

What is the CMD prompt input for tracking a network pathway to see where there may be a bottleneck in communication?

Answer 26

traceRT - finds where in the network path the problem is (where data is getting stuck/stopped) by tracking the EXACT path that data takes to its destination, each time it encounters a Router (hop) on route it reports it back (the IP address and time taken between each hop/router) for example type tracert 8.8.8.8

Question 27

What do you type into CMD prompt to display what devices are currently connected to your device and what ports are open/listening on your device?

Answer 27

netstat -a

Question 28

How do you show the network configuration of your device in CMD prompt?

Answer 28

ipconfig/all - shows detailed TCP/IP config information which is very useful for troubleshooting network issues the device may be having.

Question 29

How do you view a list of all the sub commands/switches of a CMD prompt command?

Answer 29

Type the command and add: /?

Question 30

What does the ipconfig /flushdns CMD prompt command do?

Answer 30

Clears any IP addresses and other DNS records from your cache.

Question 31

How many data packets does the CMD prompt ping command send to the specified address?

Answer 31

It sends out 4 data packets to the specified IP address and then the IP address sends 4 packets back in response (if there is a connection route available), example: ping 8.8.8.8 (for google)

Question 32

What does WEP stand for in networking?

Answer 32

Wireless Equivalent Privacy - an outdated/rarely used encryption measure as it is easily hackable. Replaced by WPA/WPA2/WPS.

Question 33

What is WPA2 in network security?

Answer 33

Uses CCMP encryption of data.

Question 34

What is a Demilitarised Zone (DMZ) in computing?

Answer 34

Allows a designated computer to bypass using a firewall/security and be completely open to the internet by putting it in the DMZ, used for testing services e.g. to see if a firewall setting was preventing access, requires a static IP address.

Question 35

What is the Open System Interconnection model?

Answer 35

A way of visualising data transmission in a network by splitting it into 7 layers.

Question 36

What is the purpose of a Gateway network device?

Answer 36

Device that joins two or more (generally incompatible networks together) by converting the format of the data (not changing the data itself just it's structuring) so it can be understood at both ends. GATEWAY = PROTOCOL CONVERTER that allows different networks to be linked, despite different data formats.

Question 37

What does a Digital Subscriber Line (DSL) provide?

Answer 37

Internet over telephone lines by using different frequencies.

Question 38

In a drug distribution network analogy what would the Internet Protocol (IP) be represented by?

Answer 38

The roads. Ethernet cables etc carrying data packets to given delivery addresses.

Question 39

What does multiplexing allow? | (A feature provided by TCP and UDP)

Answer 39

Multiplexing allows multiple different applications to communicate with a server simultaneously (at the same time). (IP without TCP/UDP cannot do this!). It works by combining multiple data streams and types into ONE single complex data stream.

Question 40

What are some benefits of TCP IP protocol over UDP IP protocol?

Answer 40

Transmission Control Protocol is a connection/session based protocol with a 3 step formal handshake to establish/confirm a connection between two devices. TCP guarantees data delivery by sending a confirmation of receipt (ACKnowledgement) from the recipient device which allows TCP to resend and reorder any data missing/corrupted packets as necessary. TCP can also control the flow of data by slowing down the rate of transfer so the recipient device doesn't get overwhelmed.

Question 41

In the drug distribution network analogy what does the port number attached to each TCP/UDP data/drug packet do?

Answer 41

It tells the packet which application/service/drug user in the house/pc/server to go to.

Question 42

Are sending/source ports or receiving ports more commonly kept the same to avoid confusion and data traffic queues?

Answer 42

Receiving ports are commonly kept the same to avoid confusion and allow services to communicate with each other.

Question 43

Does UDP establish a connection/session?

Answer 43

No UserDatagramProtocol doesn't do any sort of formal handshake/session creation between two devices it just flings data at a device. It's one way traffic on UDP.

Question 44

What is the one main advantage UDP has over TCP data transmission?

Answer 44

UDP is a lot faster/has realtime data flow as it doesn't have to establish receipt and therefore is perfect for things like VoIP (Voice over Internet Protocol). This is because time doesn't stop for network issues so if TCP dropped a packet and had to go back and resend and reorder it would make no sense in terms of the human conversation flow. DHCP uses UDP 67/68 TFTP uses UDP 69 These Protocols do not need to receive information back.

Question 45

What is Software Defined Networking (SDN)?

Answer 45

The abstraction of physical networking tasks, jobs, traditionally performed by hardware, to a centralised network management API. Thereby allowing for more flexible and easily manageable networking.

Question 46

What are the three layers/planes of SDN?

Answer 46

Application layer - applications like security features: firewalls, IDS, IPS and network analytics apps, load balancers. Control layer - SDN controller (brain of the network) - controls physical layer devices (switches, routers, etc) and determines how traffic should flow through the network as well as managing permissions, policies, configuration, traffic optimisation. Physical (Data) Layer/plane - comprised of physical network hardware as well as virtual hardware (e.g. switches, routers). ROUTES TRAFFIC to where it is needed. Collects network statistics to display in Application layer.

Question 47

What are some negatives of SDN?

Answer 47

Highly complex setup that takes a lot of time to transition from a hardware based network, complete dependency on the SDN controller - if it fails everything grinds to a halt.

Question 48

What are the benefits of implementing SDN?

Answer 48

Scalability, cost (as don't have to run/buy as much hardware and not locked in to any specific vendor for compatibility), better network traffic flow (optimisation), centralised network management and don't have to physically swap out cables, enhanced security (as can rapidly clamp down on any intrusions across the network and roll out network wide security policies instantly).