Network Addressing and Basic Troubleshooting Module 1 – 3 Checkpoint Test Online

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Optical fiber uses light to transmit signals. Therefore, fiber-optic cable is not affected by EMI or RFI.

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In Manchester encoding, the transition occurs at the middle of each bit period. Manchester encoding is used in older Ethernet standards such as 10BASE-T. Ethernet 100BASE-X family uses 4B/5B encoding and 1000BASE-X uses 8B/10B encoding.

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STP provides better noise protection than does UTP cabling. However, compared to UTP cable, STP cable is significantly more expensive and difficult to install. If the cable is improperly grounded, the shield may act as an antenna and pick up unwanted signals.

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Copper media is widely used in network communications. However, copper media is limited by distance and signal interference. Data is transmitted on copper cables as electrical pulses. The electrical pulses are susceptible to interference from two sources: – Electromagnetic interference (EMI) or radio frequency interference (RFI) – EMI and RFI signals can distort and corrupt the data signals being carried by copper media – Crosstalk – Crosstalk is a disturbance caused by the electric or magnetic fields of a signal on one wire interfering with the signal in an adjacent wire.

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The OSI physical layer provides the means to transport the bits that make up a frame across the network media. This layer accepts a complete frame from the data link layer and encodes it as a series of signals that are transmitted to the local media.

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Bandwidth is the capacity at which a medium can carry data, so it is always higher than throughput and goodput. Goodput is throughput minus traffic overhead for establishing sessions, acknowledgments, encapsulation, and retransmitted bits, so it is always lower than throughput.

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Straight-tip connectors lock securely with a “twist-on/twist-off” bayonet-style mechanism. SC connectors are a widely-adopted LAN and WAN connector that uses a push-pull mechanism to ensure positive insertion. LC simplex connectors are a smaller version of the SC connector. A duplex multimode LC connector is similar to an LC simplex connector, but uses a duplex connector.

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Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) is a wireless technology that allows only one device to transmit on a channel at a given moment and prevents collisions from occurring.

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A logical topology usually contains relevant network configuration information, such as the following: – Device names – Device IP addressing – Network designations – Configuration information

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There are two types of topology diagrams. The logical topology uses icons to identify network devices and show how the devices are connected to the school network. The physical topology diagram shows where the network devices are actually located in each room of the school.

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The use of Layer 2 switches operating in full-duplex mode eliminates collisions, thereby eliminating the need for CSMA/CD.

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In an extended star topology, central intermediate devices interconnect other star topologies.

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Ethernet switches operate in full-duplex mode by default when powered on. Point-to-point and mesh are logical topologies.

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The mesh topology provides high availability because every node is connected to all other nodes. Mesh topologies can be found in WANs. A partial mesh topology can also be used where some, but not all, end points connect to one another.

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Hosts must maintain their own local routing table to ensure that network layer packets are directed to the correct destination network. This local table typically contains a route to the loopback interface, a route to the network that the host is connected to, and a local default route, which represents the route that packets must take to reach all remote network addresses.

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For a route to be considered a default static route it must use a network ID and subnetmask combination that will match any destination IP address. The address and mask of 0.0.0.0 0.0.0.0 in a static route will create a route table entry that matches any destination.

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Routing table entries for remote routes will have a next hop IP address. The next hop IP address is the address of the router interface of the next device to be used to reach the destination network. Directly-connected and local routes have no next hop, because they do not require going through another router to be reached.

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A default static route is used as a gateway of last resort to forward unknown destination traffic to a next hop/exit interface. The next-hop or exit interface is the destination to send traffic to on a network after the traffic is matched in a router. The route source is the location a route was learned from.

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A default gateway is only required to communicate with devices on another network. The absence of a default gateway does not affect connectivity between devices on the same local network.

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If the destination host is in the same LAN as the source host, there is no need for a default gateway. A default gateway is needed if a packet needs to be sent outside the LAN.

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There are two parts to an a network layer address, the network and host portions. Routers are not concerned about delivering packets to hosts. Routers are concerned with delivering packets to the network that a destination host is a member of.

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Light can only travel in one direction down a single strand of fiber. In order to allow for full-duplex communication two strands of fiber must be connected between each device.

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All protocols based on CSMA are nondeterministic. Ethernet implements CSMA/CD and 802.11 (wireless, not Ethernet) implements CSMA/CA. Although there are a number of methods to avoid collisions, they may occur.

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In a hybrid topology like a partial mesh topology, some devices are fully interconnected with all others while some are not.

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A logical topology describes how the hosts access the network medium, whether the network is a broadcast network, a token passing network, or any other type of network.