The Ethernet networks connected to router R1 in the graphic have been summarized for router R2
as 192.1.144.0/20. Which of the following packet destination addresses will R2 forward to R1,
according to this summary? (Choose two.)
A.
192.1.159.2
The bits on the left of multiple addresses must be identical.
The interface is shut down.
B.
192.1.160.11
Routing protocol should select route according to the 32-bit IP address and the prefix length of
the maximum 32 bit address.
No keep-alive messages are received.
C. What are possible causes for this interface status? (Choose three.)
192.1.138.41
Routing update must contain 32-bit IP address and the prefix length (subnet mask)
QUESTION 197
The show interfaces serial 0/0 command resulted in the following output. Which three are possible
reasons for this interface status? (Choose three.) 
The clock rate is not set.
D.
192.1.151.254
No loopback address is set.
E.
192.1.143.145
No cable is attached to the interface.
F.
192.1.1.144
There is a mismatch in the encapsulation type.
A.
192.1.159.2
The bits on the left of multiple addresses must be identical.
The interface is shut down.
B.
192.1.160.11
Routing protocol should select route according to the 32-bit IP address and the prefix length of
the maximum 32 bit address.
No keep-alive messages are received.
C. What are possible causes for this interface status? (Choose three.)
192.1.138.41
Routing update must contain 32-bit IP address and the prefix length (subnet mask)
QUESTION 197
The show interfaces serial 0/0 command resulted in the following output. Which three are possible
reasons for this interface status? (Choose three.)
The clock rate is not set.
A.
192.1.159.2
The bits on the left of multiple addresses must be identical.
The interface is shut down.
B.
192.1.160.11
Routing protocol should select route according to the 32-bit IP address and the prefix length of
the maximum 32 bit address.
No keep-alive messages are received.
C. What are possible causes for this interface status? (Choose three.)
192.1.138.41
Routing update must contain 32-bit IP address and the prefix length (subnet mask)
QUESTION 197
The show interfaces serial 0/0 command resulted in the following output. Which three are possible
reasons for this interface status? (Choose three.)
The clock rate is not set.
D.
192.1.151.254
No loopback address is set.
E.
192.1.143.145
No cable is attached to the interface.
F.
192.1.1.144
There is a mismatch in the encapsulation type.
Explanation:
This question is about route summary.
Example of route summary calculation
The routing table stores the following networks:
172.16.12.0/24
172.16.13.0/24
172.16.14.0/24
172.16.15.0/24Routing protocols summarize or aggregate routes based on shared network numbers within the
network. To calculate the summarized route of the router, it is necessary to determine how many
bits on the left of those addresses are the same. The steps are shown below:
Step onE. Convert addresses to binary format and align them.
Step two: Find out the identical last bit of all addresses.
Step threE. Calculate how many bits are the same. The summarized route is an IP address with a
slash, which will be helpful.
172.16.12.0/24= 172.16.000011 00.00000000
172.16.13.0/24= 172.16.000011 01.00000000
172.16.14.0/24= 172.16.000011 10.00000000
172.16.15.0/24= 172.16.000011 11.00000000
172.16.15.255/24= 172.16.000011 11.11111111
The first 22 bits of IP addresses 172.16.12.0—172.16.15.255 are identical, so the best
summarized route is 172.16.12.0/22.
Using route summary can reduce the routing items on the summarized router to decrease the
memory occupied and network traffic generated by routing protocol.
Route summary implementation:Based on the information provided in the exhibit, we know that Serial0/0 is up, line protocol is
down, usually there are three states:
1. serial0/0 up, line protocol is up The interface is up and the link protocol is up.
2. serial0/0 down, line protocol is down The interface is down and there is something wrong with
the physical layer .