CS6250 COMPUTER NETWORKS EXAM 1
TEST BANK VERIFIED QUESTIONS AND
ACCURATE RESPONSES FULL SOLUTION
⩥ How does SDX allow app-specific peering?
Answer: - identify traffic from app and direct to different path
- good for high-bandwidth apps
(8)
⩥ How does SDX allow inbound traffic engineering?
Answer: installing the switch with forwarding rules based on source IP
and source port (INSTEAD OF JUST DEST ADDRESS) enables the AS
to control how TRAFFIC ENTERS THE NETWORK
(8)
⩥ How does SDX support wide-area server load balancing?
Answer: - SDX allows us to modify packet headers
- Destination IPs can be modified at the IXP to desired backend behavior
(8)
⩥ How does SDX support redirection thru middleboxes?
,Answer: - middleboxes don't have to be placed at EVERY location in
case of geographically large ISPs
- direct traffic through a fixed set of middleboxes
- less redirection - send some traffic to a SEQUENCE of middleboxes
(8)
⩥ What are the 4 properties that ensure communication is secure even in
presence of attackers? Countermeasures for each.
Answer: 1. confidentiality
- message is only available to 2 parties
- encrypt the message
2. integrity
- message has not been modified while in transit
- check for message integrity
3. Authentication
- 2 parties are who they say they are
- authentication mechanisms
4. availability
,- communication channel is functioning properly and power
outages/attacks can be coped with
(9)
⩥ What is ultimate goal of DNS protocol abuse?
Answer: Remain undetectable longer
(9)
⩥ What is the purpose of Round Robin DNS?
Answer: - distribute load of requests to several servers at 1 location
- purpose is to distribute traffic evenly across destination IPs
(9)
⩥ How does round robin work? (RRDNS)
Answer: DNS client chooses record with a strategy
Record has a time to live (TTL) - validity of response
if lookup is repeated while mapping is active, dns client will receive set
of records in different order
, (9)
⩥ How does DNS content-based delivery work?
Answer: DNS returns IP that represents "nearest edge" server to the
client
nearest server is calculated based on network topo and characteristics of
link
TTL is LOWER than RRDNS
(9)
⩥ Why do CDNs react quicker to changes in link characteristics than
RRDNS?
Answer: Their time to live is shorter
(9)
⩥ How do CDNs and RRDNS benefit scammers?
Answer: - Harder to shut down online scams because if just one IP is
functional, it still works
(9)
⩥ How do fast flux service networks work?
TEST BANK VERIFIED QUESTIONS AND
ACCURATE RESPONSES FULL SOLUTION
⩥ How does SDX allow app-specific peering?
Answer: - identify traffic from app and direct to different path
- good for high-bandwidth apps
(8)
⩥ How does SDX allow inbound traffic engineering?
Answer: installing the switch with forwarding rules based on source IP
and source port (INSTEAD OF JUST DEST ADDRESS) enables the AS
to control how TRAFFIC ENTERS THE NETWORK
(8)
⩥ How does SDX support wide-area server load balancing?
Answer: - SDX allows us to modify packet headers
- Destination IPs can be modified at the IXP to desired backend behavior
(8)
⩥ How does SDX support redirection thru middleboxes?
,Answer: - middleboxes don't have to be placed at EVERY location in
case of geographically large ISPs
- direct traffic through a fixed set of middleboxes
- less redirection - send some traffic to a SEQUENCE of middleboxes
(8)
⩥ What are the 4 properties that ensure communication is secure even in
presence of attackers? Countermeasures for each.
Answer: 1. confidentiality
- message is only available to 2 parties
- encrypt the message
2. integrity
- message has not been modified while in transit
- check for message integrity
3. Authentication
- 2 parties are who they say they are
- authentication mechanisms
4. availability
,- communication channel is functioning properly and power
outages/attacks can be coped with
(9)
⩥ What is ultimate goal of DNS protocol abuse?
Answer: Remain undetectable longer
(9)
⩥ What is the purpose of Round Robin DNS?
Answer: - distribute load of requests to several servers at 1 location
- purpose is to distribute traffic evenly across destination IPs
(9)
⩥ How does round robin work? (RRDNS)
Answer: DNS client chooses record with a strategy
Record has a time to live (TTL) - validity of response
if lookup is repeated while mapping is active, dns client will receive set
of records in different order
, (9)
⩥ How does DNS content-based delivery work?
Answer: DNS returns IP that represents "nearest edge" server to the
client
nearest server is calculated based on network topo and characteristics of
link
TTL is LOWER than RRDNS
(9)
⩥ Why do CDNs react quicker to changes in link characteristics than
RRDNS?
Answer: Their time to live is shorter
(9)
⩥ How do CDNs and RRDNS benefit scammers?
Answer: - Harder to shut down online scams because if just one IP is
functional, it still works
(9)
⩥ How do fast flux service networks work?
