READ Free Dumps For CISCO- 100-105
| Question ID 14617 | When a router makes a routing decision for a packet that is received from one network and
destined to another, which portion of the packet does if replace?
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| Option A | Layer 2 frame header and trailer
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| Option B | Layer 3 IP address
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| Option C | Layer 5 session
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| Option D | Layer 4 protocol
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| Correct Answer | A |
Explanation Explanation: Router Switching Function (1.2.1.1)A primary function of a router is to forward packets toward their destination. This is accomplished by using a switching function, which is the process used by a router to accept a packet on one interface and forward it out of another interface. A key responsibility of the switching function is to encapsulate packets in the appropriate data link frame type for the outgoing data link. NOTE In this context, the term switching literally means moving packets from source to destination and should not be confused with the function of a Layer 2 switch. After the router has determined the exit interface using the path determination function, the router must encapsulate the packet into the data link frame of the outgoing interface. What does a router do with a packet received from one network and destined for another network? The router performs the following three major steps: ✑ Step 1. De-encapsulates the Layer 3 packet by removing the Layer 2 frame header and trailer. ✑ Step 2. Examines the destination IP address of the IP packet to find the best path in the routing table. ✑ Step 3. If the router finds a path to the destination, it encapsulates the Layer 3 packet into a new Layer 2 frame and forwards the frame out the exit interface.
| Question ID 14618 | Which feature allows a device to use a switch port that is configured for half-duplex to
access the network?
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| Option A | CSMA/CD
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| Option B | IGMP
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| Option C | port security
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| Option D | split horizon
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| Correct Answer | A |
Explanation Explanation: Ethernet began as a local area network technology that provided a half-duplex shared channel for stations connected to coaxial cable segments linked with signal repeaters. In this appendix, we take a detailed look at the half-duplex shared-channel mode of operation, and at the CSMA/CD mechanism that makes it work. In the original half-duplex mode, the CSMA/CD protocol allows a set of stations to compete for access to a shared Ethernet channel in a fair and equitable manner. The protocols rules determine the behavior of Ethernet stations, including when they are allowed to transmit a frame onto a shared Ethernet channel, and what to do when a collision occurs. Today, virtually all devices are connected to Ethernet switch ports over full-duplex media, such as twisted-pair cables. On this type of connection, assuming that both devices can support the full-duplex mode of operation and that Auto-Negotiation (AN) is enabled, the AN protocol will automatically select the highest-performance mode of operation supported by the devices at each end of the link. That will result in full-duplex mode for the vast majority of Ethernet connections with modern interfaces that support full duplex and AN.