CompTIA® Network+ Exam Notes : Repeaters, Bridges, And Routers; Spanning Tree Protocol (stp)

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11.Repeaters, Bridges, and Routers

I. Repeaters work at Physical layer (Layer 1),

II. Bridges and simple switches work at Data Link Layer (Layer 2),

III. Routers work at Network Layer (Layer 3) of ISO Reference Model.

The term "Segments" is usually associated with Transport layer

The term "Packets" is usually associated with Network Layer and

The term "Frames" is usually associated with Data Link Layer

13. Spanning Tree Protocol (STP) IEEE Specification 802.1d is used to prevent routing loops. In Cisco Catalyst 5000 series switches, use BDPUs (Bridge Protocol Data Units) to determine the spanning tree topology. STP uses a Tree Algorithm (STA) to prevent loops, resulting in a stable network topology.

14. HTTP is the protocol used for accessing the World Wide Web services. HTTP operates over TCP/IP. TCP/IP is the protocol, which is used by all internet applications such as WWW, FTP, Telnet etc. IPX/SPX is proprietary protocol stack of Novell NetWare.

15. TCP: TCP is a full-duplex, connection-oriented protocol. It incorporates error checking as well.

UDP (User Datagram Protocol): UDP is a thin protocol. UDP is a connectionless protocol. It doesn't contact the destination before sending the packet and doesn't care whether the packet is reached at the destination. UDP uses port number 6.

The port number used by TCP is 6 and that of UDP is 17.

16. Standard adopted for Ethernet CSMA/CD by IEEE Committee is 802.3. 100BaseT (Fast Ethernet) uses IEEE803.2u standard which incorporates CSMA/CD protocol.


Standard Compliance
802.3  standard for 10BaseT Ethernet CSMA/CD
802.3u IEEE standard for 100BaseT (Fast Ethernet) incorporating CSMA/CD protocol.
802.3z IEEE standard for Gigabit Ethernet
802.5 IEEE standard for Token Ring networks
802.11 IEEE standard for wireless LAN

18. Given below are the distance limitations of Fast Ethernet specification:

100BaseTX ---- Cat 5 UTP, 2 pair -------- 100 meters
100BaseT4 ----- Cat 3,4,5; UTP, 4 pair --100 meters
100BaseFX ----- MMF cable --------------- 400 meters

19. The distance specification for various media type 1000BaseXX is as given below:

1000BaseCX --- Copper shielded twisted pair---25 meters
1000BaseT------- Cat 5 UTP, 4 pair-----------------100 meters
1000BaseSX----- Multimode fiber cable -----------260 meters
1000BaseLX------ Single mode fiber cable-------- 3 km

20. 10BaseT and 100BaseT use RJ-45 type of connector. 10Base2 (also called Thinnet) uses BNC connectors for attaching work stations. BNC-T is used to connect a work station to the Thinnet coaxial cable. The BNC-T(m) connector end mates with the BNC(f) connector on the NIC card. The BNC-T(f) connector ends are attached to BNC(m) cables, that in turn attach to other computers through BNC-T connector.

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