Cis 3360 Exam 1

Front 1

The internet is made up of millions of _____ and _____

Back 1

Hosts and Routers

Front 2

The internet is a network of networks.
Tier-1 ISPs control the internet backbone (the core routers)
Lower tier ISPs _______

Back 2

Pay higher tier ISP for internet access and provide access to end users.

Front 3

Delivery of data on the internet is governed by protocol layers.
TCP and UDP are part of ______ layer

Back 3

Transport Layer Protocols– control main Host-to-host data transfer

Front 4

Delivery of data on the internet is governed by protocol layers.
FTP, HTTP, SMTP are part of _____ layer

Back 4

Application Layer – Supports network applications

Front 5

Delivery of data on the internet is governed by protocol layers.
IP addresses are part of _____ layer

Back 5

Network Layer – Supports routing of data

Front 6

Delivery of data on the internet is governed by protocol layers.
Ethernet connections are part of ________ layer.

Back 6

Link Layer – Communication between adjacent network elements (computer - computer, computer - router, etc)

Front 7

Delivery of data on the internet is governed by protocol layers.
Wire voltages & radio signals are part of ______ layer.

Back 7

Physical Layer – The "bits on the wire", the actual connections

Front 8

IP - Internet Protocol - is concerned with _________

Back 8

Concerned with routing data from host to host across the internet

Front 9

Classful addressing - list each class and it's structure

Back 9

Class A – First 1 bit fixed, 7 bits for network, 24 bits for host : [1][ 7b ][ 24b ]

Class B – First 2 bits fixed, 14 bits for network, 16 bits for host : [10][ 14b ][ 16b ]
Class C – First 3 bits fixed, 21 bits for network, 8 bits for host : [110][ 21b ][ 8b ]
Class D – First 4 bits fixed, Multicast : [1110][ 28b ]
Class E – First 4 bits fixed, Reserved for future use : [1111][ 28b ]

Front 10

IP Addresses are running out, how is this being mitigated?

Back 10

NAT – Network Address Translation – Many computers share a few IP Addresses, requires a special router
Classless InterDomain Routing (CIDR) – Classful addressing has been mostly abandoned

Front 11

What is CIDR based on?
List the notation for CIDR.

Back 11

CIDR is based on Variable Length Subnet Masking (VLSM)

a.b.c.d/n where n specifies the network prefix length. (How many bits make up the network address.)

Front 12

Plaintext = ?
Ciphertext = ?

Back 12

Plaintext is the unencrypted, original message to be sent.
Ciphertext is the encrypted message to be sent.

Front 13

Cipher = ?
Key = ?

Back 13

Cipher – Algorithm to convert between plaintext and ciphertext

Key – Additional information needed as part of the cipher

Front 14

Encipher (encrypt) = ?
Decipher (decrypt) = ?

Back 14

Encipher (encrypt) – Convert plaintext to ciphertext

Decipher (decrypt) – Convert ciphertext to plaintex

Front 15

Cryptography = ?
Cryptanalysis = ?
Cryptology = ?

Back 15

Cryptography – Developing ciphers

Cryptanalysis – Obtaining plaintext from ciphertext without the key

Cryptology – Combined fields of cryptography and cryptanalysis. The study of ciphers in general

Front 16

Symmetric Key Cipher = ?
Public Key Cipher = ?

Back 16

Symmetric Key Cipher - The same key is used for both encryption and decryption

Public Key Cipher - Different keys are used for encryption and decryption

Front 17

Substitution ciphers = ?
Monoalphabetic Cipher = ?
Polyalphabetic Cipher = ?

Back 17

Substitution Cipher – Replace characters with other characters

Monoalphabetic Cipher - Each time a character appears in plaintext, it is replaced with the same ciphertext character

Polyalphabetic Cipher - A given plaintext character can be replaced in many different ways

Front 18

Transposition Ciphers = ?

Back 18

Transposition Ciphers - Rearranging the plaintext characters without changing them otherwise

Front 19

Concerning Cipher Security:
Computational security = ?
Unconditional Security = ?

Back 19

Computational security – Can't be cracked in a reasonable amount of time without key (granted by modern ciphers)

Unconditional Security – Can't be cracked without the key at all (difficult to achieve practically)

Front 20

How does a Virus work?
How do viruses propagate?

Back 20

Viruses infect files or system areas.

Viruses propagate to other computers when files are transferred.

Front 21

What is a worm?
How do they propagate?

Back 21

Worms are standalone code.

Worms propagate through network vulnerabilities.

Front 22

What is a Trojan Horse?
How do they propagate?

Back 22

Trojan Horses masquerade as legitimate programs, but often open "backdoor" vulnerabilities in systems.

Trojan Horses do not propagate unless the file is transferred.

Front 23

What are the two phases of a virus?
What are the two types of viruses?

Back 23

Infection phase - Infect files & Execution phase - Do stuff (cause harm).

Boot sector virus - infects the boot sector of a disk.
File virus - infects programs or data files.

Front 24

What are the ways viruses infect files?

Back 24

Overwrite - just write over code.
Append - add code to the end of the program.
Prepend - add code to the beginning of the program
Cavity filling - fill in empty space of the program with virus code.

Front 25

What are the ways we can detect viruses?

What is a type of virus that can avoid some of these detections?

Back 25

File size changes - If a virus has infected a file, the file size will increase due to added code.
File checksum changes - a mathematical process to generate a unique code for a file, if a virus infects the file, this code will change.
Signature-based detection - if we know viruses coding, we can check known viruses against files to see if they are infected.

Polymorphic viruses change their form to avoid signature based detection.