Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Systems and Networks > Distributed Systems > Flashcards

Distributed Systems Flashcards

(92 cards)

Start Studying
1
Q

What are the two ways a hard drive disk is split up?

A

Into:
- Sectors (like pizza slices)
- Tracks (concentric rings)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does ‘block’ describe in terms of a hard drive disk?

A

The areas between sector boundaries and track boundaries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is a cylinder in relation to hard disk drives?

A

A collection of tracks with the same index number

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

When does fragmentation occur in hard disk storage?

A

When storage is lost due to a block being underused and files are fit into leftover spaces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What happens when a hard disk is more fragmented?

A

The disk head spends more time moving back and forth and the read/write efficiency decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What memory does a solid state drive use?

A

Flash memory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How does a solid state drive differ from a hard disk?

A

Solid state drive has no moving parts so no read/write head and no platter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is a solid state drive made of?

A

Transistors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the advantages of a solid state drive over a hard disk?

A

-Faster than hard drive
- Quieter, uses less power
- More tolerant to being moved

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is partitioning?

A

The traditional method where disks are divided and each partition is used for a specific purpose and can’t overflow into other sections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What do we use now instead of disk partitioning?

A

Volume management

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the features of a logical volume?

A
  • can span more than one physical hard drive
  • several physical hard drives are seen as one big disk
  • LVs can be resized easily
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does RAID mean?

A

Multiple physical disk drives forming a logical unit of storage
(redundant array of independent disks)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are four benefits of RAID?

A

Reliability, performance, capacity, availability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are index nodes (inodes)?

A

Structures that store information about each unix file

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does an inode store for regular files, directory files, and special files?

A

regular, directory: location of disk blocks
special file: identifies peripherals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How many inodes can a file have?

A

Always 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What do inodes store for all file types?

A
  • file type
  • file permissions
  • owner
  • hard link count
  • last modification time and last access time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is a boot block?

A

The first logical block disk that contains executable code for when UNIX is first activated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is a superblock?

A

Second logical block of a disk that contains info about the disk including bitmap of free blocks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the first two logical blocks of a disk?

A

1 bootblock
2 superblock

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is mounting?

A

File systems from other devices can be attached to the original directory hierarchy - can be done automatically when booting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What does mounting allow?

A

Allows users to access files seamlessly even when they’re on other devices

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How are large unix systems usually stored?

A

Over many devices with each device holding a subtree

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What are some features of NFS (network files system)?
- widely available - clients mount partitions of a server as though the partitions were physically connected
26
What does NFS allow low cost computers to do?
Share the same high capacity disk
27
What are the two ways mounting can be set up for workstations using NFS?
- mounting at boot time - mounting when referenced
28
How are files represented on NFS mounted filesystems?
file handles
29
What does it mean when an NFS file handle is opaque?
A client can't interpret it
30
What does it mean for an NFS file handle to have meaning?
A server can interpret the contents of it
31
What are the three key parts of a UNIX file handle?
- file identifier - file system identifier - generation count (incremented each time a file is unlinked and recreated)
32
What do NFS file handles not include? and why?
A pathname, this can change while a file is being accessed
33
What two protocols is NFS based on?
MOUNT NFS
34
What is the MOUNT protocol used for in NFS?
initial negotiation between NFS client and server - allowing the client to know which file systems are available and what their file handles are And used to mount remote directories to the client's local file system.
35
What is the NFS protocol used for in NFS?
- allows users to perform file and directory operations
36
What does SAMBA do?
Allows UNIX filesystems to be shared to windows and makes the UNIX file systems look like windows filesystems - and can allow UNIX systems to access windows filesystems
37
Describe the client-server model in simple terms.
The client (application on your machine) contacts the server which accepts instructions and returns data
38
What two pieces of software are involved in email
- email interface program - mail transfer program
39
What are the 3 main categories of protocols used within email?
Transfer, access, representation
40
What does a transfer protocol do within email?
Protocol used to move a copy of an email message from one computer to another
41
What does an access protocol do within email?
Allows a user access to their mailbox and to send and receive messages
42
What does a representation protocol do within email?
Specifies the format of an email message when stored on disk
43
What does SMTP stand for? What is it?
Simple Mail Transfer Protocol, it's the standard protocol used by mail transfer programs
44
What does SMTP do?
Transfers text, allows sender to specify recipients name and check them, sends only one copy of a given message
45
What actions are possible as part of mail access?
A user can view their mailbox, view headers, download, delete or send messages
46
Why do ISPs offer email services?
Because most users do not leave their computer running all the time and don't know how to configure email
47
When ISPs run email services, what do they provide users with?
a mailbox for each user and an interface for them to view it with, with special purpose interface applications for mobile devices
48
What does POP stand for? What is it?
Post Office Protocol, a mail access protocol
49
What does IMAP stand for?
Internet Mail Access protocol
50
What basic services are offered by both POP and IMAP?
- users can access mailbox - users can view headers, download, delete, send - Email client runs on user's personal computer - server runs on computer where the mailbox is stored
51
What are the two ways of representing email messages?
RFC2822 mail message format - MIME (multi-purpose internet mail extensions)
52
What does MIME stand for?
Multi-purpose Internet Mail Extensions
53
How are emails represented using RFC2822?
- Mail message represented as a text file consisting of: header, blank line, body
54
How are email messages represented using MIME?
- extends SMTP so images and binary data can be represented - users can divide messages into several parts so image attachment can be encoded differently from a spreadsheet - emails are displayed as more than plain text
55
What does FTP stand for?
File transfer protocol
56
What are some characteristics of FTP?
- arbitrary file contents - bidirectional transfer - support for authentication and ownership - ability to browse folders' - textual control messages
57
What common action is FTP the common protocol for?
Users requesting a download from a browser
58
What are the two types of connection made by FTP?
Control connection AND data connection
59
What does DNS stand for?
Domain Name System
60
What is DNS for?
Translating between symbolic names and IP addresses
61
Who uses DNS?
Applications (which then becomes a client to the DNS server)
62
How are domain names structured?
Hierarchically, most important on the right e.g. marian.cs.nott.ac.uk
63
DNS database is a ____ system
distributed
64
When an application acts as a client, what resolution does it request?
recursive
65
When a server acts a client what resolution does it request?
iterative
66
What are the three main aspects of computer security?
Confidentiality Integrity Availability
67
What are the three things we are trying to achieve with computer security?
- Authentication - Authorisation - Non-repudiation
68
What does confidentiality mean? And what can it encompass?
Means keeping information secret from those who should not know it encompasses: privacy and secrecy
69
What does integrity mean in computer security?
Ensuring things are not altered without permission
70
What does maintaining integrity require?
Only authorised users perform authorised actions on resources they are authorised to use
71
What does availability mean in computer security?
Ensuring that legitimate users of a system have reasonable and reliable access to their systems
72
What is cryptography?
The use of a key to encode/decode a message
73
What are the two types of key encryption?
Secret key encryption and public key encryption
74
What are three methods for maintaining data security?
- hash functions - cryptography - digital signatures and digital certificates
75
What is the purpose of digital signatures and certificates?
Verify integrity of data and identity of sender
76
What is a hash function?
An algorithm that transforms a message into a fixed length hash key (hash)
77
How does public key encryption work?
Messages are encrypted using public key - messages are decoded with secret key
78
What is a common use of public key encryption?
Secure web purchases
79
What is a drawback of secret key encryption?
You need to keep the secret key secret and also send it to the other party for decoding
80
What is the purpose of a digital signature?
For the receiver to be certain that the message is from a particular sender
81
Summarise digital certificates.
- Used to authenticate a user, device, or server - Issued by trusted third party, CA - Contains: certified public keys, information about certificate holder
82
What is proven when digital signatures are used together with digital certificates?
- Sender is authentic, message has not been tampered with
83
What does VPN stand for?
Virtual Private Network
84
What are two methods of network security?
-VPNs - Firewalls
85
What does a VPN do?
It's a connection which makes a remote network appear as if its directly connected with encrypted traffic
86
What must VPNs ensure happens to packets on their path?
That once packets are encrypted by Ipsec they are not fragmented along the path
87
What does a firewall do?
Allow partial connected to the internet while retaining some isolation
88
Where are firewalls placed?
Between an organisation internal network and the external network
89
What do firewalls control and limit?
- control amount of traffic passing between internal and external network - limits amount of damage
90
What can firewalls filter?
- filter packets from a particular source - filter traffic for a particular service - filter traffic from a particular source or port number
91
What are 2 types of firewalls?
Packet filters (chokes) Proxies (gates)
92
What is a demilitarised zone in the context of a network firewall?
A section of devices offered limited protection

Systems and Networks (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions