Domain 4 - Communications and Networking Flashcards
Simplex
one-way communication (one system transmits, the other listens)
Half-duplex
communication sends or receives one at a time (only one can transmit at a time) like a Walkie Talkie
full-duplex
communication is cable of sending and receiving simultaneously (both system talking at the same time)
baseband
one channel, one signal at a time. ethernet is baseband
broadband
multiple channels and all channels can send and receive multiple signals at a time
Internet
a global connection of peered WAN networks (patchwork of ISPs)
intranet
an organizations privately owned network, houses companies specific information. Example: how do I contact HR, what are policies and procedures.
extranet
Private intranets that are connected. maybe these are business partners or in very large companies, all the child companies intranets connect to the extranet
circuit switching
expensive
used less often
always available
guaranteed bandwidth
always takes the same path
packet switching
cheap
ISP oversubscribes lines
people very seldom use what they pay for
packets take multiple different paths to destination
packets are reassembled at destination
QOS
(Quality of service) give specific traffic priority over other traffic
most commonly used for VOIP or other UDP (connection less) traffic needing close to real time communication
TCP
connection oriented
sequential - each packet is reassembled in the order it was sent
even with packets tacking different paths, this still happens
we use TCP for things that requires data integrity and can handle less delivery time
PAN
personal area network — your personal area
LAN
local area network - devices are nodes and are geographically constrained
MAN
metropolitan area network - usually spans a city or large campus
WAN
wide area network – covers a large geographic network area such as a city, country or even intercontinental distances. combines many types of media, telephone, cables and air waves.
VPN
virtual private network
GAN
global area network -
used for supporting mobile users across a number of wireless LANs, satellite coverage area. The transition from one to the next can be seamless
uses different technologies and protocols to make sure that user can continue to use their phone
OSI model Layers 1-7
1 - Physical
2 - Data Link
3 - Network
4 - Transport
5 - Session
6 - Presentation
7 - Application
We are blocking unused ports on our servers as part of our server hardening, when we block TCP/UDP port 138. Which protocol are we blocking?
Netbios datagram service
We are using the OSI model to categorize attacks and threats. Which of these are COMMON layer 2 threats?
A: Ping of death
B: syn floods
C: arp spoofing
D: eavesdropping
C: arp spoofing
Explanation
ARP spoofing is an attack where an attacker sends a fake ARP (Address Resolution Protocol) messages over a local area network. This results in associating the attacker’s MAC address with the IP address of an authorized computer or server on our network.
In a new data center implementation, we are wanting to use IPv6 addresses. Which of these statements are TRUE about IPv6 addresses? (Select all that apply).
A: they can use EUI/MAC48 addresses by adding ffe in the midle of the mac address
B: they use broadcast addresses
C: they are 32-bit binary
D: they are 128 bit binary
A and D
Explanation
IPv6 is 128-bit binary, often expressed in hexadecimal numbers (using 0-9 and a-f); for Link Local addresses we add the fe80: prefix to an address, and for EUI/MAC48 addresses we add “fffe” to make it an EUI/MAC64 address.
Which layer of the Open Systems Interconnect (OSI) model isolates traffic into broadcast domains?
Explanation
Layer 3: Network Layer: Expands to many different nodes (IP) – The Internet is IP based. Isolates traffic into broadcast domains.
know the IPV4 private addresses
- 0.0.0 - 10.255.255.255.
- 16.0.0 - 172.31.255.255
- 168.0.0 - 192.168.255.255
which port is used by our DHCP servers to communicate with the clients
Explanation
DHCP uses UDP Port 67 for the DHCP Server and UDP Port 68 for the Client.
A system is requesting an IP address using DHCP. how would the traffic flow look
- Discovery
- offer
- request
- acknowledge
Which of the following proxies cannot make access decisions based upon protocol commands?
A. Application
B. Packet filtering
C. Circuit
D. Stateful
answer is C.
Application and circuit are the only types of proxy-based firewall solutions listed here. The others do not use proxies. Circuit-based firewalls make decisions based on header information, not the protocol’s command structure. Application-based proxies are the only ones that understand this level of granularity about the individual protocols.
Alice wants to send a message to Bob, who is several network hops away from her. What is the best approach to protecting the confidentiality of the message?
A. PPTP
B. S/MIME
C. Link encryption
D. SSH
Answer is B.
Secure Multipurpose Internet Mail Extensions (S/MIME) is a standard for encrypting and digitally signing e-mail and for providing secure data transmissions using public key infrastructure (PKI).
what does TCP stand for in TCP/IP
- Transmission control protocol
- part of a suite of communication protocols
- defines how applications create communication
- manages how messages are broken down into packets to be transmitted and reassembled at the destination
what does IP stand for in TCP/IP
- Internet Protocol
- part of a suite of protocols
- defines how to address and route packets for delivery
how many layers are in TCP/IP and what are they in order (bottom to top)
• 4 (Link or Physical, network, transport, application)
what does PDU stand for
• protocol data units
Name the PDU and layer it is associated with in the OSI model
- data - session, presentation and application layer
- segments - transport layer
- packets - network layer
- frames - data link layer
- bits - physical layer
what two things were behind the design of TCP/IP
- network reliability
- auto recovery from failure
what layers does the link layer in TCP/IP map to in OSI
• link/physical in tcp/ip maps to (physical and data layers in the OSI model)
what does network layer in TCP/IP map to in OSI
• same -network layer in OSI
what does transport layer in TCP/IP map to in OSI
• same - transport layer in OSI
what does the application layer in TCP/IP map to in OSI
TCP/IP application layer maps to (session, presentation and application in the OSI model)