Refer to the exhibit.
Hosts in network 192.168.2.0 are unable to reach hosts in network 192.168.3.0. Based on the
output from RouterA, what are two possible reasons for the failure? (Choose two.)
A.
The cable that is connected to S0/0 on RouterA is faulty.
B.
Interface S0/0 on RouterB is administratively down.
C.
Interface S0/0 on RouterA is configured with an incorrect subnet mask.
D.
The IP address that is configured on S0/0 of RouterB is not in the correct subnet.
E.
Interface S0/0 on RouterA is not receiving a clock signal from the CSU/DSU.
F.
The encapsulation that is configured on S0/0 of RouterB does not match the encapsulation that
is configured on S0/0 of RouterA.
s0/0 is up/down, that’s a problem there (L2 problem – possibly clock rate or encapsulation mismatch).
s0/1 is shut down, we don’t care about it, it’s just one other interface on the router
B is incorrect because s0/1 does not affect the routing process. it’s true that that interface is down, but that’s not part of the problem
A -> the serial cable connects the serial interfaces on the two routers. Nothing wrong.
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A CSU/DSU is a digital-interface device used to connect a data terminal equipment (DTE), such as a router, to a digital circuit, such as a Digital Signal 1 (T1) line. The CSU/DSU implements two different functions. The channel service unit (CSU) is responsible for the connection to the telecommunication network, while the data service unit (DSU) is responsible for managing the interface with the DTE.
There are a couple of different clock settings associated with a CSU/DSU (internal, recovered, loop). When you are receiving a signal (clocking) from a service provider, you should always use recovered clocking (prevents slips because of different synchronization between you and the provider). Internal clocking works okay (not very reliable) if you are providing the reference, but for the other devices will need to be set for recovered.
channel service unit (CSU)
is used to perform loopback testing,
may perform bit stuffing,
may also provide a framing and formatting pattern compatible with the network.
The purpose of the DSU is to transfer serial data synchronously between the WAN port and the DTE ports.
encapsulation dot1Q
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To enable IEEE 802.1Q encapsulation of traffic on a specified subinterface, use the encapsulation dot1q command. To disable encapsulation, use the no form of this command.
encapsulation dot1Q vlan-id
no encapsulation dot1Q vlan-id
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S0/0 status up, protocol down – unable to communicate – different encapsulations
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In computer networking, encapsulation is a method of designing modular communication protocols in which logically separate functions in the network are abstracted from their underlying structures by inclusion or information hiding within higher level objects.
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s0/0 is up/down, L2 problem – clock rate or encapsulation mismatch
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