Deck 5: Internet Control Message Protocol

Question 1

Routers send ICMP Redirect messages to hosts to indicate that a preferable route exists.

Answer 1

True

Question 2

ICMP packets contain only three required fields after the IP header: Type, Code, and Checksum.

Answer 2

True

Question 3

Which of the following can hackers can use as part of a reconnaissance process to learn about active network addresses and active processes?

A)availability
B)ICMP
C)auto recovery
D)presence

Answer 3

B

Question 4

What protocol protects the authentication and confidentiality of ICMPv6 exchanges?

A)IPsec
B)WPA2
C)PPTP
D)SHA-2

Question 5

Which of the following message types document when routing or delivery errors prevent IP datagrams from reaching their destinations?

A)ICMP Echo/Echo Reply
B)ICMP Source Quench
C)ICMP Time Exceeded
D)ICMP Destination Unreachable

Question 6

Which of the following utilities use route tracing to identify a path from the sender to the target host?

A)gateway
B)Traceroute
C)firewalking
D)auto-recovery

Question 7

Routers can use ICMP to provide a default gateway setting to a host (if the host requests assistance).

Question 8

A host or router can send which of the following error message to indicate that the protocol defined in the IP header cannot be processed?

A)Code 2: Protocol Unreachable
B)Code 3:Port Unreachable
C)Code 4: Fragmentation Needed and Don't Fragment Was Set
D)Code 5: Source Route Failed

Question 9

Which of the following types of messages serves to keep hosts apprised of networking conditions and problems, and equipped to use best paths around the network?

A)NTP messages
B)Path MTU messages
C)ICMP messages
D)GMT messages

Question 10

Which message type supports functionality for reachability utilities like Ping and Tracert; essential when installing, configuring, and troubleshooting IP networks?

A)ICMP Echo/Echo Reply
B)ICMP Source Quench
C)ICMP Time Exceeded
D)ICMP Destination Unreachable

Question 11

Which RFC defines a method for discovering a Path MTU (PMTU) using ICMP?

A)RFC 1191
B)RFC 1241
C)RFC 1542
D)RFC 1577

Question 12

Which of the following message types permit a gateway (router) on a nonoptimal route between sender and receiver to redirect traffic to a more optimal path?

A)ICMP Echo/Echo Reply
B)ICMP Source Quench
C)ICMP Redirect
D)ICMP Destination Unreachable

Question 13

With router advertising, the default Lifetime value for route entries is 10 minutes.
Indicate the answer choice that best completes the statement or answers the question.

Question 14

Using which of the following as well as some manipulation of the TTL value in the IP header, Traceroute results provide a list of routers along a path, as well as the round-trip latency time to each router?

A)ICMP Echo Requests
B)ICMP paths
C)ICMP metrics
D)ICMP query messages

Question 15

The value 0 in the IP header Protocol field denotes that an ICMP header follows the IP header.

Question 16

Which of the following typically learn about routes through manual configuration of the default gateway parameter and redirection messages?

A)Packets
B)Firewalls
C)Ports
D)IP hosts

Question 17

Which of the following processes is one method of obtaining a list of the active hosts on a network?

A)ICMP query
B)query
C)IP address scanning
D)firewalking

Question 18

Which of the following enables a source to learn the currently supported MTU across an entire path, without requiring fragmentation?

A)Firewalking
B)Traceroute
C)Pathping
D)PMTU Discovery

Question 19

Which of the following ICMP packet fields provide error detection for the ICMP header only?

A)Checksum
B)Type
C)Host
D)Code

Question 20

Which of the following may a router or host use as a way to indicate that it is becoming congested or overloaded?

A)Checksum
B)Source Quench
C)GMT
D)PMTU

Question 21

For any network node to communicate and exchange data with another network node, some way of forwarding packets from the sender to receiver must exist. What is this concept called?

A)response time
B)route tracing
C)reachability
D)network congestion
Enter the appropriate word(s) to complete the statement.

Question 22

Match each item with a statement below.
a.Network congestion
b.firewalking
c.ICMP query message
d.inverse mapping
e.ICMP Echo communication
f.overhead
g.reachability
h.throughput difference
i.restricting link
the comparative difference in throughput between two paths and is measured in Kbps or Mbps

Question 23

Match each item with a statement below.
a.Network congestion
b.firewalking
c.ICMP query message
d.inverse mapping
e.ICMP Echo communication
f.overhead
g.reachability
h.throughput difference
i.restricting link
a condition that occurs when the delivery time for packets increases beyond normal limits

Question 24

Of which of the following ICMP replies are there two versions, which are: the standard version that simply states the packet had the Don't Fragment bit set when it reached a router that needed to fragment it, and the PMTU version that includes information about the restricting link?

A)Code 2: Protocol Unreachable
B)Code 3: Port Unreachable
C)Code 4: Fragmentation Needed and Don't Fragment Was Set
D)Code 5: Source Route Failed

Question 25

If configured to do so, routers periodically send unsolicited ICMP Router Advertisements to which of the following all-hosts multicast address?

A)224.0.0.1
B)255.255.0.0
C)224.255.0.1
D)255.224.0.1

Question 26

Match each item with a statement below.
a.Network congestion
b.firewalking
c.ICMP query message
d.inverse mapping
e.ICMP Echo communication
f.overhead
g.reachability
h.throughput difference
i.restricting link
the process of identifying live network hosts positioned behind a filtering device by probing for addresses known not to be in use

Question 27

Match each item with a statement below.
a.Network congestion
b.firewalking
c.ICMP query message
d.inverse mapping
e.ICMP Echo communication
f.overhead
g.reachability
h.throughput difference
i.restricting link
a two-staged reconnaissance method involving an initial perimeter device discovery phase and subsequent inverse mapping of filtered devices

Question 28

The PMTU specification defined in RFC 1191 requires the PMTU host to try periodically a larger MTU to see if the ____________________ has increased.

Question 29

Match each item with a statement below.
a.Network congestion
b.firewalking
c.ICMP query message
d.inverse mapping
e.ICMP Echo communication
f.overhead
g.reachability
h.throughput difference
i.restricting link
the non-data bits or bytes required to move data from one location to another

Question 30

____________________ describes the concept of walking a firewall ACL or ruleset to determine what it filters, and how.

Question 31

Which of the following ICMP Types is used for Echo Request packets?

A)ICMP Type 2
B)ICMP Type 4
C)ICMP Type 6
D)ICMP Type 8

Question 32

Two of the most well-known utilities, Ping and Traceroute, rely on ICMP to perform connectivity tests and ____________________.

Question 33

ICMP Type ____________________ is used for Echo Reply packets.

Question 34

Match each item with a statement below.
a.Network congestion
b.firewalking
c.ICMP query message
d.inverse mapping
e.ICMP Echo communication
f.overhead
g.reachability
h.throughput difference
i.restricting link
an ICMP message that contains requests for configuration or other information

Question 35

Match each item with a statement below.
a.Network congestion
b.firewalking
c.ICMP query message
d.inverse mapping
e.ICMP Echo communication
f.overhead
g.reachability
h.throughput difference
i.restricting link
a link that does not support forwarding based on the current packet format and configuration

Question 36

Match each item with a statement below.
a.Network congestion
b.firewalking
c.ICMP query message
d.inverse mapping
e.ICMP Echo communication
f.overhead
g.reachability
h.throughput difference
i.restricting link
the ability to find at least one transmission path between a pair of hosts so they can exchange datagrams across an internetwork

Question 37

An IP ____________________ is performed by sending a ping packet (ICMP Echo Request packet) to each host within a range and noting the responses.

Question 38

Match each item with a statement below.
a.Network congestion
b.firewalking
c.ICMP query message
d.inverse mapping
e.ICMP Echo communication
f.overhead
g.reachability
h.throughput difference
i.restricting link
an ICMP process whereby a host sends an Echo packet to another host on an internetwork

Question 39

Which ICMP reply does a router send in order to indicate that the router cannot use the strict or loose source routing path specified in the original packet?

A)Code 2: Protocol Unreachable
B)Code 3: Port Unreachable
C)Code 4: Fragmentation Needed and Don't Fragment Was Set
D)Code 5: Source Route Failed

Question 40

Which of the following is a command-line utility that uses ICMP Echo packets to test router and link latency, as well as packet loss?

A)NTP
B)Pathping
C)Path MTU
D)Traceroute

Question 41

Describe the ICMP message Code 3 Port Unreachable.

Question 42

Briefly describe an ICMP redirect attack.

Question 43

What is firewalking?

Question 44

What is the purpose of the following ICMP message types: ICMP Redirect, ICMP Time Exceeded, and ICMP Parameter Problem?

Question 45

According to RFC 792, what is the relationship between IP and ICMP?

Question 46

Describe some of the security issues for ICMPv6.

Question 47

Briefly describe an ICMP router discovery attack.

Question 48

How does inverse mapping determine live targets on a network?

Question 49

Briefly describe the fields that are included in the ICMPv4 Router Advertisement packets (after the ICMP Checksum field).

Question 50

Briefly define the following codes, currently assigned to the ICMP Destination Unreachable type number: Code 2: Protocol Unreachable, Code 3:Port Unreachable, and Code 5: Source Route Failed.