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CCNA (200 - 301) Official Cert Guide Chapters 1 - 3 (2022)

Scott Jones Computer Networking IT Certification Inglés 141 fichas

Fichas del conjunto (141)

  1. 1What is SFPSmall form-factor pluggable. They are ports used for fiber connections.
  2. 2What interfaces are SFP/SFP+ be used on?SFP : Gigabit interfaces
    SFP+ : 10Gbps interfaces
  3. 3What is multimode fiber?An LED emits light at multiple angles into the core. It uses a wider core than single-mode.
  4. 4What is single-mode fiber?A laser based transmitter send light through the core at a single angle. It uses a narrower core than multimode.
  5. 5Why are fiber cables more secure than UTP?UTP emits a faint signal outside the cable, the transmitted data is at risk of being intercepted.
  6. 6What is a multicast address?The address used by a subset of devices on the LAN that volunteer to receive data.
  7. 7What is the MAC?All devices are assigned a unique Media Access Control address. Specifically, the address is assigned to individual NICs. It allows them to be identified on networks for sending and receiving frames.
  8. 8What is a broadcast address?It is used for sending data to all devices on the Ethernet LAN. The address is FFFF:FFFF:FFFF
  9. 9List 4 alternative names for the MAC address.Ethernet, NIC, LAN, and Unicast address.
  10. 10How many bytes in a MAC address?6-bytes
  11. 11How many bits are in a single hex digit?4 bits
  12. 12How many bits in a byte?8 bits in a byte
  13. 13How are MAC addresses unique?NIC manufacturers get a 3-byte organisationally unique identifier (OUI) from the IEEE. The OUI is used on the first half of the MAC address. For the last half the manufacturers produces their own random 3-byte value (vendor assigned).
  14. 14What is half duplex logic?The device must wait to send if it is receiving a frame; it cannot send and receive simultaneously.
  15. 15What is full duplex logic?A node does not have to wait on other devices as it can send and receive frames at the same time.
  16. 16Acronym 'CSMA/CD'Carrier Sense Multiple Access With Collision Detection
  17. 17The CSMA/CD algorithm is used with LANs using what device?Hubs
  18. 18Should ports connecting to a LAN hub use full duplex or half duplex logic?Half duplex
  19. 19Why is it important to understand CSMA/CD? Why not just use full duplex logic?Occasionally you will find hubs being used in some enterprise networks. Full duplex does not work on hubs, the CSMA/CD algorithm must be used.
  20. 20In simple terms, what does CSMA/CD do?It alleviates collisions by managing how devices recover from a collision and resend frames.
  21. 21On a LAN using a hub, does everything have to use half duplex logic, or would it only be the ports directly connected to the hub?Only the ports connected to the hub.
  22. 22On LANs using hubs, what are collisions?Collisions are when multiple frames collide during transmission because hubs support only 1 frame in transmission at a time.
  23. 23What is meant by a hub flooding frames?For data to reach its destination, the hub will simultaneously transmit frames out to all other ports.
  24. 24What are the advantages of hub ports using half duplex logic?It helps prevent collisions because devices must wait for the traffic to be clear before sending data.
  25. 25What are the limitations of half duplex logic ?Collisions still happen because when the traffic is clear, any waiting nodes will transmit at the same time.
  26. 26Name three application layer protocols.HTTP, POP3, SMTP
  27. 27Name the major protocol in the network layer.Internet Protocol (IP)
  28. 28What are the wired and wireless protocols used in the data link layer?Ethernet & 802.11
  29. 29Name two transport layer protocols.Transmission Control Protocol (TCP) and User Datagram Protocol (UDP)
  30. 30Explain how a webpage gets from a server to a browser in the application layer.The browser sends a GET request to the server. The name of the file is in the HTTP header. The server responds with an OK message and sends part of the file. Subsequently it sends more data over until all the contents of the file a received.
  31. 31As a server responds to a request for a file, an OK message is also known as what?code 200
  32. 32A server sends over the first part of the requested file to a web browser. Do the other parts of the file sent over have HTTP headers?No, only the first part of the file.
  33. 33Explain what TCP is and how it works.TCP is for error recovery. If parts of the requested file are lost, TCP will send another request to send the data.
  34. 34How do sequence numbers work with TCP?Each part of a requested file is sent over in sequence numbers. If one of these sequences are missing, the TCP logic on the receiving side can request the data again as soon as it notices.
  35. 35What is HTTP?Hyper Text Transfer Protocol. It allows web browsers to request web pages and servers to send the contents.
  36. 36What is IP and how does it work?A network layer protocol that deals with addressing, how to group addresses, and is essential for the routing process. It places data in packets containing the destination and source address.
  37. 37Forwarding an IP packet is also known as...Routing
  38. 38What is the Ethernet protocol?It defines the Ethernet frame. The IP packet is encapsulated and the frame and its data is transmitted. When it reaches it next destination it is de-encapsulated.
  39. 39What is 802.11The wireless protocol.
  40. 40What three layers on the OSI model are considered as the application layer on the TCP/IP model. List these layers from top to bottom.Application
    Presentation
    Session
  41. 41What are the terminologies used when data is encapsulated at the transport, data link, and network layersTCP Segment, IP Packet, and Ethernet Frame
  42. 42Why is the OSI model relevant?The numberings are still used for reference. For example, L4PDU etc.
  43. 43What is a protocol data unit (PDU)?It is used in OSI referencing when talking about encapsulated data at different layers.
  44. 44An L2PDU is on what layer?Data Link Layer
  45. 45An L4PDU is on what layer?Transport Layer
  46. 46What is the IEEE?The Institute of Electrical and Electronics Engineers. They develop communication and network standards
  47. 47What is same layer interaction?Two computers use a protocol to communicate with each other on the same layer.
  48. 48What is adjacent layer interaction?Adjacent layers on the same computer work together.
  49. 49What do switches do?Multiple devices will plug into a switch which will establish a LAN connection for them by plugging into a router.
  50. 50What do routers do?Routers connect the LAN to the WAN and
  51. 51What does a transceiver do?They transmit and receive data at the same time.
  52. 52What is a node?Networking devices that transmit and receive data.
  53. 53What is meant by Ethernet?A family of standards defining how to send data over cables and the protocols/rules that nodes must follow to be part of an Ethernet LAN.
  54. 54Ethernet Frame. What does the preamble do?Simply put, it deals with synchronisation.
  55. 55Ethernet Frame. What does the start frame delimiter (SFD) do?It signifies that the next byte begins the destination MAC address field.
  56. 56Ethernet Frame: What does the Type field contain?The type of L3PDU in the frame, typically an IP packet (IPv4 or IPv6).
  57. 57Ethernet Frame. What does the data and padding field contain?Data from a higher layer, typically a network layer packet. The sender adds padding to meet the minimum of 46 bytes required.
  58. 58Data Link Layer Frames. What does the frame check sequence (FCS) field do?It allows the receiving node to detect errors in the frame. It is the only field in the Ethernet trailer.
  59. 59How does the frame check sequence (FCS) work?The sender and receiver apply a math formula to the frame, if the receiver does not get the same result as the sender, it means the frame has changed during transmission, it is then discarded.
  60. 60What is Ethernet shared media.Also known as shared media network. Networks that use hubs, CSMA/CD and share bandwidth.
  61. 61What is Ethernet point-to-pointA network built with switches; each (point to point) link works independently of the others. Frames can be sent on every link at the same time.
  62. 62What are UTP cables?Unshielded Twisted Pair. An Ethernet cable with RJ-45 connectors. The wires are twisted in two pairs or four pairs depending on the speed.
  63. 63A UTP with two twisted wire pairs works up to what speeds?10BASE-T and 100BASE-T
  64. 64A UTP cable with 4 twisted pairs works up to what speeds?1000BASE-T
  65. 65What are RJ-45s?The Ethernet ports and connectors. The connectors have 8 pin positions where the wires plug into.
  66. 66Ethernet Frame. What is the minimum and maximum bytes in the data and padding?46 - 1500
  67. 67What is a crossover cable?It is an Ethernet cable that swaps the pin logic on either end. Pins 1,2 on one end will connect to pins 3,6 on the other end. It is used when similar devices are connecting such as two switches or two PCs.
  68. 68What makes a straight-through cable different from a crossover cable?The straight-through doesn't swap the pin logic because it is used for two 'un-like' devices to connect such as a wireless AP to a switch.
  69. 69Why does pin logic matter?If devices trying to connect are transmitting and receiving on the same Ethernet cable pin positions, they will not connect. The device type therefore determines the cable type.
  70. 70What does auto-mdix do?It allows devices with Gigabit Ethernet functionality to change the cable's logic if the wrong type is used.
    Without Gigabit Ethernet support, a crossover cable is essential.
  71. 71What is EMI?Electromagnetic Interference. As electrical circuits pass over the wires, it creates interference with the signals. Twisting wires helps reduce EMI.
  72. 72What is crosstalk?It is when EMI takes place between different wire pairs in the same cable.
  73. 73What does the term 'burned-in address' imply?It's another name for the Ethernet MAC address. The MAC address is permanently encoded into the ROM chip on the NIC by the manufacturer.
  74. 74Where is half duplex logic used?It is used on any ports connecting to a LAN hub.
  75. 75What is the cladding used for in fiber cables?Reflecting light back into the core
  76. 76What is an encoding scheme?It is what devices use to transmit data as bits.
  77. 77What is 'IETF' and what do they do?The Internet Engineering Taskforce. They create new TCP/IP standards.
  78. 78What is a telco?A telephone company, they will create leased lines for WAN access.
  79. 79What is the serial link on a router for?Connecting to a leased line.
  80. 80How do serial links transmit data?It uses full-duplex logic with two wire pairs, one pair for each direction.
  81. 81Were does a telco place their networking equipment?Central Offices.
  82. 82How does a leased line reach customers?The telco establishes a WAN across a large area (city/country) by linking their COs. From the COs cables are installed to other buildings in preparation for selling their service.
  83. 83What is a T1?A specific type of leased line transmitting data at 1.544 Mbps.
  84. 84What are 5 other names for a leased line?Leased circuit
    Serial line/link,
    Point-to-point line/link
    WAN Link
    Private Line
  85. 85What data-link protocols are used by leased lines?Point-to-Point Protocol (PPP)
    High-Level Data Link Control (HDLC)
  86. 86List 5 HDLC fields.Flag, Address, Control, 'Type', FCS
  87. 87HDLC, what is the purpose of the flag field?It is found at the start and end of the frame. It lets nodes know that anew frame is coming and when it has ended.
  88. 88HDLC, what is the control field?It is not important by today's standards but it is used the process of communication.
  89. 89HDLC, what is the address field used for?To show where the frame is going.
  90. 90HDLC, what makes the Type field different?HDLC does not inherently use a Type field. Vendors need to insert their own. When the Type field is inserted, the HDLC becomes a proprietary protocol and will not work with other vendor's HDLC.
  91. 91Why is Ethernet better than leased lines?It is faster, cheaper, and quicker to get installed.
  92. 92Fiber links such as 1000BASE-ZX make Ethernet a viable WAN technology. What distance does this support?70km
  93. 93What is a point of presence (PoP)?It is the local access point to an ISP. A fiber cable links the customer site to the PoP.
  94. 94What is EoMPLSEthernet over Multiprotocol Label Switching - It is a technology used in creating Ethernet services.
  95. 95Name two common names (not including EoMPLS) used for an Ethernet WAN.Ethernet Line Service (E-Line)
    Ethernet Emulation
  96. 96When transmitting frames over an Ethernet WAN, why does the destination MAC address change?The destination MAC address relates to the next-hop router. A new MAC address is encapsulated with the frame across each point.
  97. 97A host on a network is another name for what?A computer
  98. 98How do hosts choose where to send IP packets?They use TCP/IP software embedded in their OS.
  99. 99What is a routing table?A table with entries to particular network destination. Routers use them for routing.
  100. 100What is a subnet?Part of the IP address. All devices on a LAN share the same subnet and are grouped together. When a packet contains an IP address with a different subnet it will be routed to another LAN.
  101. 101Create IPv4 addresses for two devices on the same subnet.The first art of the addresses should match. You should have something like:
    170.83.41.55
    170.83.41.113
  102. 102How many bytes are in an IPv4 header?20-bytes
  103. 103How many bits are in the destination and source address fields in the IPv4 header?Each are 32 bits in length
  104. 104For a host to send packets to remote destination, what does it need to know about its own LAN?The IP address of their default gateway.
  105. 105What do routers need to know before they can forward packets?The routes the packet will take.
  106. 106What are routing protocols used for?They enable routers to exchange routing information such as different subnets.
  107. 107What is an internetwork?Two or more networks connected by routers, switches, cables, and other equipment.
  108. 108What does the routing protocol enable routers to do?Exchange routing protocol messages and learn routes for all known IP routes.
  109. 109What is a routing update?A routing protocol message which tells a router's neighbours about all routes in its routing table.
  110. 110What is DNS?Domain Name System. It enables a computer to retrieve an IP address to connect to a server by typing the domain name.
  111. 111What is a DNS query?It is when a PC asks the DNS server for the IP address of the server it wants to connect to. The domain name will be sent through the DNS query.
  112. 112What is a DNS reply?This is when the DNS server responds to a DNS query by sending back the requested server's IP address.
  113. 113What address is used when a router forwards a DNS message?The IP packet will contain the DNS server's address as the destination.
  114. 114Does a DNS server know every domain name? Explain.No. The information is distributed across many DNS servers working together and forwarding queries to each other.
  115. 115What is ARP?Address resolution protocol. It enables hosts or routers to dynamically learn the MAC address of another host or router on the LAN.
  116. 116Where do LAN devices store the MAC address of other devices?The ARP table/cache
  117. 117What causes the reoccurrence of ARP requests?Devices will occasionally clean out their ARP cache.
  118. 118What is an ARP request and how does it work?An ARP request is when a device wants to learn the MAC address of another device. A MAC broadcast is transmitted through the LAN with the frame's IP packet containing the target destination address. The associated device will reply back with its MAC address.
  119. 119What is an ARP reply message?When a device receives the ARP request, it will respond with the reply message containing its IP and MAC address.
  120. 120How would you look at the your computer's ARP cache?Open the command terminal and type 'arp -a'
  121. 121What is the ping command?It is an internet control message protocol (ICMP). It sends an echo request to another IP address, if the device gives an echo reply it means packets can be delivered from one host to another and back.
  122. 122An IP network is also known as a what?An IP subnet.
  123. 123What is a unicast IP address?It is a single address, it will be the destination address in the IP packet.
  124. 124How is an ARP message broadcasted?The Ethernet frame needs a destination MAC address, but the whole point in an ARP request is to learn the MAC address. The message is therefore broadcasted using the broadcast address in the frame (FFFF.FFFF.FFFF)
  125. 125On LANs using hubs, what causes collisions?The nature of hubs flooding frames is the prime cause for this collisions. Two or more devices sending frames at the same time will cause collisions.
  126. 126What are fiber optic cables made of?Fiberglass, a long thing strand of flexible glass.
  127. 127What runs along the length of a fiber cable?A glass or plastic core.
  128. 128What does a fiber optical transmitter do?It shines light into the core, the light passes through the glass.
  129. 129State the common name associated with 10MbpsEthernet
  130. 130State the common name associated with 100MbpsFast Ethernet
  131. 131How fast is Gigabit Ethernet?1000Mbps
  132. 13210Gbps is known by its common name as what?10 Gig Ethernet
  133. 133State the formal IEEE name for 10BASE-T802.3
  134. 134State the formal IEEE name for 100BASE-T802.3u
  135. 135State the formal IEEE name for 1000BASE-LX802.3z
  136. 136State the formal IEEE name for 1000BASE-T802.3ab
  137. 137State the formal IEEE name for 10GBASE-T802.3an
  138. 1381000BASE-LX supports a cable length of up to what?5000m
  139. 139A router is sending an IP packet to a device on a local subnet, what will the router lookup as it encapsulates the packet?The ARP table for the device's MAC address.
  140. 140Ethernet Frame: How is the type field distinguished?Hex numbers
  141. 141Besides encapsulation, what does a router do with an IP packet?It compares its destination address to its known IP routes and forwards the packet.

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These flashcards detail Chapters 1 - 3 from the official CCNA Cert Guide Book. My CCNA quiz has additional resources and I recommend studying both as they contain different formats and cover different topics. This is developed from my own note taking. The information should be fairly accurate, but as a learner, my own interpretation of the source material may not be 100% accurate. Consult official Cisco material for full exam coverage.
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Scott Jones
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