Key Security Objectives correct answers Confidentiality, Integrity, Availability
Internetworking correct answers Involves connecting the many different types of LANs/WANs
together to allow any computer to communicate with any other computer, regardless of what
LAN/WAN they are connected to (eg, Internet Protocol)
Layered Internet Protocol Stack correct answers Application -> transport -> network -> link ->
physical (top down)
Application Layer correct answers Supporting network applications (HTTP, IMAP, SMTP, DNS)
Transport Layer correct answers Process-process data transfer (TCP, UDP)
Network Layer correct answers Routing of datagrams from source to destination (IP, routing
protocols)
Link Layer correct answers Data transfer between neighboring network elements (Ethernet,
WiFi, PPP)
Physical Layer correct answers Bits "on the wire", pushing the bits along (coaxial cable, fiber
optic cable)
IPv4 correct answers 32 bits, 2^32 IPs
IPv6 correct answers 128 bits, 2^128 IPs
OSI reference model correct answers Has two layers not featured in Internet Protocol Stack:
presentation, session. Application -> presentation -> session -> transport -> network -> data link
-> physical (top down)
,OSI presentation layer correct answers Transforms the data it receives into a format that can be
read by the application layer. The data encoding and decoding done here depend on the
application layer protocol. This layer also handles several forms of encryption and decryption.
OSI session layer correct answers Manages the dialog, or session between two computers; it
establishes, manages, and terminates this connection among all communicating devices.
IEEE 802 Address (MAC) correct answers 48-bits, 24-bits assigned by IEEE to the
manufacturer, the second 24-bits assigned by the manufacturer to the device. LAN cards get
these.
Switched Ethernet Topology correct answers Hosts, routers, connect to switch on a port. All
frames between stations pass via switch. Switch stores address on other end of link and port in
memory for forwarding frames.
IP Datagram Format correct answers TTL (remaining max hops, decremented at each router),
source IP, dest. IP, upper layer protocol (TCP, UDP), length (bytes), header checksum (check if
header contains errors when received by the destination), payload data (variable length, typically
a TCP or UDP segment)
IPv4 (split) correct answers Split into network and host portions (network identifies a subnet in
the Internet while host identifies an IP device in that subnet)
Classful Subnet Masks (not used anymore) correct answers Class A: 24 bits for hosts
Class B: 16 bits for hosts
Class C: 8 bits for hosts, home network
Classless Subnet Masks correct answers 32-bits Identifies where the IP address is split between
network and host portion.
1: network
, 0: host
Hosts allowed for a Subnet Mask of 255.255.252.0/22 correct answers 2^10 - 2 = 1022 hosts
2^22 = 4M subnets
All bits are 1s (255.255.255.255) for dest. correct answers Local broadcast address, identifies all
hosts on the current subnet
Startup Source Address correct answers Identifies host if currently it has no address; all bits are 0
Directed Broadcast Address correct answers Identifies all hosts on a specific subnet, all bits in
host portion are 1s.
Operating system correct answers Manages activities and resources of a computer (acts as a
interface between the hardware and the user)
Kernel correct answers The lowest-level core of an operating system (heart of OS, interacts with
hardware and most tasks like memory management, task scheduling, and file management)
Shell correct answers An interactive program that uses user input to manage the execution of
other programs. A command processor.
exit correct answers logs out of shell
ls correct answers lists file in a directory
pwd correct answers print the current working directory
cd correct answers changes the working directory