Possible Questions: List the TCP Control Mechanisms. Control the rate of traffic Limit the number of unacknowledged packets Additive-Increase/Multiplicative-Decrease Slow Start Fast Retransmit / Fast Recovery What is the primary function of TCP congestion control? Match the transmission rate of the sender to that of the receiver as well as the network, thus reducing the amount of dropped packets. What is a TCP congestion window size? The amount of received data that can be buffered during a connection. This is the amount of data that can be sent without receiving an ACK.
What are the major functions of DNS(domain name system)? 1) mapping the host name and the IP address 2) referring the mail server which handles e-mails
Question: What is the purpose of ECML Version 2.0? Answer: To extend the functionality of version 1.0 and 1.1 to allow for two way communication between the seller and buyer, to encompass more payment methods, and to improve the overall functionality of the language.
Use the Diffie-Hellman Key Exchange method to find the secret shared number s between Bob and Alice for the following parameters: For p = 23 (a prime number) And g = 5 (primitive mod p) And a=6 (Alice’s secret number) And b=15 (Bob’s secret number) Find s their secret shared number.
Answer: The Diffie-Hellman Key Exchange is a cryptographic protocol that allows two parties that have no prior knowledge of each other to jointly establish a shared secret key over an insecure communications channel.
1.Alice and Bob agree to use a prime number p=23 and base g=5. 2.Alice chooses a secret integer a=6, then sends Bob (g^a mod p)= 5^6 mod 23 = 8. 3.Bob chooses a secret integer b=15, then sends Alice (g^b mod p)= 5^15 mod 23 = 19. 4.Alice computes (g^b mod p)^a mod p = 19^6 mod 23 = 2. 5.Bob computes (g^a mod p)^b mod p = 8^15 mod 23 = 2. Both Alice and Bob have arrived at the same value s=2, because g^(ab) and g^(ba) are equal. Only a, b and g^(ab) = g^(ba) are kept secret.
Question: What does RADIUS stand for and what is the shared secret used for?
RADIUS - Remote authentication dial in user service.
A shared secret is known by the user and the server. If the server challenges the user, it will be required to encrpyt an unpredictable number in order for the server to validate their request.
What is one of the problems with TCP over 2.5/3G Wireless Networks?
TCP is optimized for wired networks. 2.5/3G is Wireless Networks. Packet loss in TCP is assummed to be because of congestion or timeouts. In wireless networks packet loss in more often due to loss of signal. When packet loss in TCP occurs, this causes the TCP receiver to close its window and in return makes the TCP sender reduce the number of packets being sent. This is fine if the packet lass was due to congestion. However, if the packet loss was due to loss of signal, performance suffers. With loss of signal, the TCP sender should increace the the number of packets sent instead of decrease.
Possible Questions: Do a problem of Dijkstra’s Algorithm? How does ARP work? What is the function of ARP? To resolve IP Addresses into Physical Addresses. How does NAT work? How does ARP poisoning work? How can a hidden station problem be avoided?
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Possible Questions:
List the TCP Control Mechanisms.
Control the rate of traffic
Limit the number of unacknowledged packets
Additive-Increase/Multiplicative-Decrease
Slow Start
Fast Retransmit / Fast Recovery
What is the primary function of TCP congestion control?
Match the transmission rate of the sender to that of the receiver as well as the network, thus reducing the amount of dropped packets.
What is a TCP congestion window size?
The amount of received data that can be buffered during a connection. This is the amount of data that can be sent without receiving an ACK.
Questions:
What is the first requirment for a message to be encrypted with PGP?
It must first be in MIME canonical format.
What is the reason for using asymmetric encryption in later versions of PGP?
The uses do not have to exchange keys ahead of time, and the user uses the sender's private key to decrypt the message.
What is a disadvantage of asymmetric encryption?
It is less efficient.
What are the major functions of DNS(domain name system)?
1) mapping the host name and the IP address
2) referring the mail server which handles e-mails
Q What are the common threats to DNS security.
A
-Footprinting
-Denial-of-service attack
-Data modification.
-Redirection.
Why don't you post a few more questions Crystal? I don't think you've listed enough...try to make them harder too!
Question:
What is the purpose of ECML Version 2.0?
Answer:
To extend the functionality of version 1.0 and 1.1 to allow for two way communication between the seller and buyer, to encompass more payment methods, and to improve the overall functionality of the language.
Use the Diffie-Hellman Key Exchange method to find the secret shared number s between Bob and Alice for the following parameters:
For p = 23 (a prime number)
And g = 5 (primitive mod p)
And a=6 (Alice’s secret number)
And b=15 (Bob’s secret number)
Find s their secret shared number.
Answer:
The Diffie-Hellman Key Exchange is a cryptographic protocol that allows two parties that have no prior knowledge of each other to jointly establish a shared secret key over an insecure communications channel.
1.Alice and Bob agree to use a prime number p=23 and base g=5.
2.Alice chooses a secret integer a=6, then sends Bob (g^a mod p)= 5^6 mod 23 = 8.
3.Bob chooses a secret integer b=15, then sends Alice (g^b mod p)=
5^15 mod 23 = 19.
4.Alice computes (g^b mod p)^a mod p = 19^6 mod 23 = 2.
5.Bob computes (g^a mod p)^b mod p = 8^15 mod 23 = 2.
Both Alice and Bob have arrived at the same value s=2, because g^(ab) and g^(ba) are equal. Only a, b and g^(ab) = g^(ba) are kept secret.
Possible Questions
List the 4 ARP message types.
1. ARP request
2. ARP reply
3. Reverse ARP request
4. Reverse ARP reply
How long do ARP cache table entries last?
approx. 20 mins
Possible Questions
Question 1
List the 4 ARP message types.
1. ARP request
2. ARP reply
3. Reverse ARP request
4. Reverse ARP reply
Question 2
How long do ARP cache table entries last?
approx. 20 mins
Why don't you post a few more questions Jane Wade and try to make it a little harder too!
Question:
What does RADIUS stand for and what is the shared secret used for?
RADIUS - Remote authentication dial in user service.
A shared secret is known by the user and the server. If the server challenges the user, it will be required to encrpyt an unpredictable number in order for the server to validate their request.
More people better start posting or we're all going to bomb the final...
Last call for blogs. Only those posted before 4:00 pm today (Monday, Dec 04) will be considered.
What are two ways applications try to counteract the effects of a jitter?
answer:
1. buffering data
2. delaying playback
What is address management?
answer:
The selection and synchronization of address allocation.
What is one of the problems with TCP over 2.5/3G Wireless Networks?
TCP is optimized for wired networks. 2.5/3G is Wireless Networks. Packet loss in TCP is assummed to be because of congestion or timeouts. In wireless networks packet loss in more often due to loss of signal. When packet loss in TCP occurs, this causes the TCP receiver to close its window and in return makes the TCP sender reduce the number of packets being sent. This is fine if the packet lass was due to congestion. However, if the packet loss was due to loss of signal, performance suffers. With loss of signal, the TCP sender should increace the the number of packets sent instead of decrease.
What is the bandwidth if the maximum data rate is 180 kilobits/sec and the number of discrete levels is 64?
H is bandwidth
V is discrete levels
max bps = 2Hlog(base 2)V
180000 = 2Hlog(base 2) 64
solving for H
H = 180000/2log(base2)64
H = 15 kHz
-Bryan Price
Possible Questions:
Do a problem of Dijkstra’s Algorithm?
How does ARP work?
What is the function of ARP? To resolve IP Addresses into Physical Addresses.
How does NAT work?
How does ARP poisoning work?
How can a hidden station problem be avoided?
As persistance goes down on a p-persistant CSMA protocol what happens to throughput? Why?
Throughput goes up because when it actually does send it is more likely to be received. The problem is when will the thing ever send? Almost never!
What does RFC stand for?
-
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