15. Networking Concepts Flashcards

1
Q

What is a network?

A

2 or more computers linked together to share data

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2
Q

What are network clients?

A

Computers & software that request resources from servers

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3
Q

Purpose of network protocols?

A

assign unique addresses to hosts & define packet structures for communication

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4
Q

What is a packet?

A

A wrapper for network data units

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5
Q

What do packets generally consist of?

A
  • Header
  • Payload

Header = protocol type, source address, destination address, erorr correction information, etc.
Payload = Data

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6
Q

What does network encapsulation mean?

A

A packet from 1 protocol can be wrapped within the packet from another

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7
Q

Primary protocol of the Internet & WWW?

A

TCP/IP

TCP/IP is also the primary porotocol for many private internets (networks that connect LANs together)

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8
Q

What is TCP/IP?

A

Suite of network transport protocols

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9
Q

TCP/IP layers?

A
  1. Application
  2. Transport
  3. Internet
  4. Link

These layers work together to enable communication between devices over a network, with each layer handling specific tasks and responsibilities.

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10
Q

What does the link layer do?

A

Puts frames onto the physical network.

At this layer, various networking technologies like Ethernet or Wi-Fi are used for local communication. Data is packaged into frames, but TCP/IP protocols are not utilized, and communication is limited to the local network segment.

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11
Q

What do the Internet layer protocols do?

A

Encapsulates packets into datagrams & handles routing between networks

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12
Q

3 protocols used in the Internet layer?

A
  • IP
  • ARP
  • ICMP
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13
Q

Meaning of ARP?

A

Address Resolution Protocol

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14
Q

Meaning of ICMP?

A

Internet Control Message Protocol

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15
Q

TCP’s Internet layer protocols

What does the IP protocol do?

A

Facilitates logical addressing & packet routing

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16
Q

TCP’s Internet layer protocols

What does the ARP protocol do?

A

Maps MAC addresses to IP addresses

This makes it possible for packet delivery

Hosts broadcast ARP messages onto the local network to find out which host MAC address “owns” a particular IP address. If the destination host responds, the frame can be delivered. Hosts also cache IP:MAC address mappings for several minutes to reduce the number of ARP messages that have to be sent.

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17
Q

TCP’s Internet layer protocols

What does the ICMP protocol do?

A

Reports packet delivery errors

18
Q

What do the transport layer protocols do?

A

Provides communication sessions between computers.

Each application protocol is identified at the transprt layer by a port number

19
Q

2 protocols used in the transport layer?

A
  • TCP
  • UDP
20
Q

Meaning of TCP?

A

Transmission Control Protocol

21
Q

Meaning of UDP?

A

User Datagram Protocol

22
Q

TCP transport layer protocols

What does TCP protocol do?

A

Provides connection-oriented packet delivery

The delivery is reliable & packets are delivered in correct sequence

23
Q

TCP transport layer protocols

What does UDP protocol do?

A

Provides connectionless packet delivery

UDP lacks sequencing guarantees, necessitating application-layer handling of any associated unreliability. Yet, its efficiency stems from minimal processing overhead, rendering it faster than TCP.

24
Q

What do application layer protocols do?

A

Provides communication formats for exchanging data between hosts

i.e. transmitting an email or requesting a webpage

These protocols define the structure, syntax, and semantics of the messages or data packets being exchanged, ensuring compatibility and proper interpretation by both the sender and the receiver (i.e. HTTP, SMTP, FTP, DNS, etc.)

25
Q

What is a hardware/MAC address

MAC = Media Access Control

A

48-bit hex value assigned to a network adapter

i.e. 00:60:8c:12:3a:bc or 00608c123abc or 0060.8c12.3abc

26
Q

What do hosts use ARP for if the destination IP address is local?

within the same network ID as the source

A

To discover the local destination host

27
Q

What do hsots use ARP for if the destination IP address isnt local?

Meaning the source & destination IP addresses have different network IDs

A

To discover a router on the local segment

(its default gateway). The router forwards the packet to its destination (if known), possible via intermediate routers

28
Q

What is DNS?

A

Hierarchical client/server-based name system

It resolves resource names to IP addresses

29
Q

What does a recursive query in DNS mean?

A

Local name server must resolve the name for the client

The server must actively resolve the query itself, rather than redirecting the client to another server.

30
Q

What does an iterative query in DNS mean?

A

DNS server respons with the best info it has, even if it doesnt have a complete answer

when a local name server queries a top-level domain (TLD) server (like “.com”), it doesn’t expect that server to have information about other TLDs (like “.org”). Instead, the TLD server may refer the local name server to another server that handles “.org” queries.

31
Q

What does a URL consist of?

A
  • Protocol
  • Host Location
  • File path
32
Q

What does the URL’s Protocol component mean?

A

The access method or service type being used

URLs can be used for protocols other than HTTP/HTTPS. The protocol is followed by the characters ://

33
Q

What does the URL’s Host Location component mean?

A

IP address or FQDN

34
Q

What does the URL’s File path component refer to?

A

The directory & file name location of the resource, if required

The file path may or may not be case-sensitive, depending on how the server is configured. If no file path is used, the server will return the default (home) page for the website.

35
Q

Purpose of HTTP?

A

To enable clients to request resources from HTTP servers

The clients are usually web browsers

A client connects to the HTTP server via TCP port (usually port 80), submits a request with a URL. The server acknowledges and returns the data.

36
Q

What websites does HTTP serve?

A

HTML webpages

HTML web pages are plain text files with coded tags describing how pages should be formatted

37
Q

HTTPS port?

HTTPS = HTTP over SSL (aka HTTP Secure)

A

443

38
Q

Key features of a packet switching network?

A

Network nodes forward packets, enabling them to use any available path

39
Q

What protocol is usually used to provide logical addressing on networks?

A

Internet Protocol (IP)

40
Q

What does the “/” mean in subnet masks?

i.e. /28

A

The first X bits of the subnet mask are 1s

i.e. /28 means 255.255.255.240 (11111111.11111111.11111111.11110000)