This exam will cover material from Modules 4, 6 and 7 of the CCNA1 - Introduction to Networks v7.0 (ITN) curriculum.
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Which two devices commonly affect wireless networks? (Choose two.)
Correct: Radio Frequency Interference (RFI) is the interference that is caused by radio transmitters and other devices that are transmitting in the same frequency.
Which two statements describe the services provided by the data link layer? (Choose two.)
Correct: The data link layer is divided into two sub layers, namely Logical Link Control (LLC) and Media Access Control (MAC). LLC forms a frame from the network layer PDU into a format that conforms to the requirements of the network interface and media. A network layer PDU might be for IPv4 or IPv6. The MAC sub layer defines the media access processes performed by the hardware. It manages the frame access to the network media according to the physical signaling requirements (copper cable, fiber optic, wireless, etc.)
Match the situation with the appropriate use of network media.
Correct:
Options matched to the correct selection.
| Copper Cables | Fiber optic | Wireless |
|---|---|---|
| horizontal cabling structure | backbone cabling in an enterprise | guest access in a coffee shop |
| desktop PCs in offices in an enterprise | long-haul networks | waiting rooms in a hospital |
Partly correct:
Options matched to the correct selection.
| Copper Cables | Fiber optic | Wireless |
|---|---|---|
| horizontal cabling structure | backbone cabling in an enterprise | guest access in a coffee shop |
| desktop PCs in offices in an enterprise | long-haul networks | waiting rooms in a hospital |
Incorrect:
Options matched to the correct selection.
| Copper Cables | Fiber optic | Wireless |
|---|---|---|
| horizontal cabling structure | backbone cabling in an enterprise | guest access in a coffee shop |
| desktop PCs in offices in an enterprise | long-haul networks | waiting rooms in a hospital |
What is the auto-MDIX feature on a switch?
Correct: The auto-MDIX enables a switch to use a crossover or a straight-through Ethernet cable to connect to a device regardless of the device on the other end of the connection.
What is the function of the CRC value that is found in the FCS field of a frame?
Correct: The CRC value in the FCS field of the received frame is compared to the computed CRC value of that frame, in order to verify the integrity of the frame. If the two values do not match, then the frame is discarded.
What is the purpose of the FCS field in a frame?
Correct: The FCS field in a frame is used to detect any errors in the transmission and receipt of a frame. This is done by comparing the CRC value within the frame against a computed CRC value of the frame. If the two values do not match, then the frame is discarded.
What is contained in the trailer of a data-link frame?
Correct: The trailer in a data-link frame contains error detection information that is pertinent to the frame included in the FCS field. The header contains control information, such as the addressing, while the area that is indicated by the word "data" includes the data, transport layer PDU, and the IP header.
What is the auto-MDIX feature?
Correct: The auto-MDIX feature allows the device to configure its network port according to the cable type that is used (straight-through or crossover) and the type of device that is connected to that port. When a port of a switch is configured with auto-MDIX, this switch can be connected to another switch by the use of either a straight-through cable or a crossover cable.
Which statement describes a characteristic of the frame header fields of the data link layer?
Correct: All data link layer protocols encapsulate the Layer 3 PDU within the data field of the frame. However, the structure of the frame and the fields that are contained in the header vary according to the protocol. Different data link layer protocols may use different fields, like priority/quality of service, logical connection control, physical link control, flow control, and congestion control.
A network team is comparing physical WAN topologies for connecting remote sites to a headquarters building. Which topology provides high availability and connects some, but not all, remote sites?
Correct: Partial mesh topologies provide high availability by interconnecting multiple remote sites, but do not require a connection between all remote sites. A mesh topology requires point-to-point links with every system being connected to every other system. A point-to-point topology is where each device is connected to one other device. A hub and spoke uses a central device in a star topology that connects to other point-to-point devices.
Refer to the exhibit. What is the destination MAC address of the Ethernet frame as it leaves the web server if the final destination is PC1?
Correct: The destination MAC address is used for local delivery of Ethernet frames. The MAC (Layer 2) address changes at each network segment along the path. As the frame leaves the web server, it will be delivered by using the MAC address of the default gateway.
Which is a multicast MAC address?
Correct: Multicast MAC addresses begin with the special value of 01-00-5E.
A network administrator is connecting two modern switches using a straight-through cable. The switches are new and have never been configured. Which three statements are correct about the final result of the connection? (Choose three.)
Correct: Modern switches can negotiate to work in full-duplex mode if both switches are capable. They will negotiate to work using the fastest possible speed and the auto-MDIX feature is enabled by default, so a cable change is not needed.
Which two fields or features does Ethernet examine to determine if a received frame is passed to the data link layer or discarded by the NIC? (Choose two.)
Correct: An Ethernet frame is not processed and is discarded if it is smaller than the minimum (64 bytes) or if the calculated frame check sequence (FCS) value does not match the received FCS value. Auto-MDIX (automatic medium-dependent interface crossover) is Layer 1 technology that detects cable straight-through or crossover types. The source MAC address is not used to determine how the frame is received. CEF (Cisco Express Forwarding) is a technology used to expedite Layer 3 switching.
A Layer 2 switch is used to switch incoming frames from a 1000BASE-T port to a port connected to a 100Base-T network. Which method of memory buffering would work best for this task?
Correct: With shared memory buffering, the number of frames stored in the buffer is restricted only by the of the entire memory buffer and not limited to a single port buffer. This permits larger frames to be transmitted with fewer dropped frames. This is important to asymmetric switching, which applies to this scenario, where frames are being exchanged between ports of different rates. With port-based memory buffering, frames are stored in queues that are linked to specific incoming and outgoing ports making it possible for a single frame to delay the transmission of all the frames in memory because of a busy destination port. Level 1 cache is memory used in a CPU. Fixed configuration refers to the port arrangement in switch hardware.
What is one advantage of using the cut-through switching method instead of the store-and-forward switching method?
Correct: Cut-through switching provides lower latency switching for high-performance computing (HPC) applications. Cut-through switching allows more invalid frames to cross the network than store-and-forward switching. The cut-through switching method can make a forwarding decision as soon as it looks up the destination MAC address of the frame.
What are two examples of the cut-through switching method? (Choose two.)
Correct: Store-and forward switching accepts the entire frame and performs error checking using CRC before forwarding the frame. Store-and-forward is often required for QOS analysis. Fast-forward and fragment-free are both variations of the cut-through switching method where only part of the frame is received before the switch begins to forward it.
Which frame forwarding method receives the entire frame and performs a CRC check to detect errors before forwarding the frame?
Correct: Fast-forward and fragment-free switching are variations of cut-through switching, which begins to forward the frame before the entire frame is received.
Which switching method has the lowest level of latency?
Correct: Fast-forward switching begins to forward a frame after reading the destination MAC address, resulting in the lowest latency. Fragment-free reads the first 64 bytes before forwarding. Store-and-forward has the highest latency because it reads the entire frame before beginning to forward it. Both fragment-free and fast-forward are types of cut-through switching.
Which media communication type does not require media arbitration in the data link layer?
Correct: Half-duplex communication occurs when both devices can both transmit and receive on the medium but cannot do so simultaneously. Full-duplex communication occurs when both devices can transmit and receive on the medium at the same time and therefore does not require media arbitration. Half-duplex communication is typically contention-based, whereas controlled (deterministic) access is applied in technologies where devices take turns to access the medium.
Which statement describes an extended star topology?
Correct: In an extended star topology, central intermediate devices interconnect other star topologies.
A network administrator is measuring the transfer of bits across the company backbone for a mission critical financial application. The administrator notices that the network throughput appears lower than the bandwidth expected. Which three factors could influence the differences in throughput? (Choose three.)
Correct: Throughput usually does not match the specified bandwidth of physical links due to multiple factors. These factors include, the amount of traffic, type of traffic, and latency created by the network devices the data has to cross.
What is a characteristic of the LLC sublayer?
Correct: The Logical Link Control (LLC) defines the software processes that provide services to the network layer protocols. The information is placed by LLC in the frame and identifies which network layer protocol is being used for the frame. This information allows multiple Layer 3 protocols, such as IPv4 and IPv6, to utilize the same network interface and media.
What type of communication rule would best describe CSMA/CD?
Correct: Carrier sense multiple access collision detection (CSMA/CD) is the access method used with Ethernet. The access method rule of communication dictates how a network device is able to place a signal on the carrier. CSMA/CD dictates those rules on an Ethernet network and CSMA/CA dictates those rules on an 802.11 wireless LAN.
In addition to the cable length, what two factors could interfere with the communication carried over UTP cables? (Choose two.)
Correct: 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:
Which advantage does the store-and-forward switching method have compared with the cut-through switching method?
Correct: A switch using the store-and-forward switching method performs an error check on an incoming frame by comparing the FCS value against its own FCS calculations after the entire frame is received. In comparison, a switch using the cut-through switching method makes quick forwarding decisions and starts the forwarding process without waiting for the entire frame to be received. Thus a switch using cut-through switching may send invalid frames to the network. The performance of store-and-forward switching is slower compared to cut-through switching performance. Collision detection is monitored by the sending device. Store-and-forward switching does not use IPv4 Layer 3 and 4 information for its forwarding decisions.
What are three ways that media access control is used in networking? (Choose three.)
Correct: Wired Ethernet networks use CSMA/CD for media access control. IEEE 802.11 wireless networks use CSMA/CA, a similar method. Media access control defines the way data frames get placed on the media. The controlled access method is deterministic, not a contention-based access to networks. Because each device has its own time to use the medium, controlled access networks such as legacy Token Ring do not have collisions.
During the encapsulation process, what occurs at the data link layer for a PC connected to an Ethernet network?
Correct: The Ethernet frame includes the source and destination physical address. The trailer includes a CRC value in the Frame Check Sequence field to allow the receiving device to determine if the frame has been changed (has errors) during the transmission.
What three items are contained in an Ethernet header and trailer? (Choose three.)
Correct: Layer 2 headers contain the following:
Refer to the exhibit. What is wrong with the displayed termination?
Correct: When a cable to an RJ-45 connector is terminated, it is important to ensure that the untwisted wires are not too long and that the flexible plastic sheath surrounding the wires is crimped down and not the bare wires. None of the colored wires should be visible from the bottom of the jack.
Refer to the exhibit. The PC is connected to the console port of the switch. All the other connections are made through FastEthernet links. Which types of UTP cables can be used to connect the devices?
Correct: A straight-through cable is commonly used to interconnect a host to a switch and a switch to a router. A crossover cable is used to interconnect similar devices together like switch to a switch, a host to a host, or a router to a router. If a switch has the MDIX capability, a crossover could be used to connect the switch to the router; however, that option is not available. A rollover cable is used to connect to a router or switch console port.
What are two characteristics of fiber-optic cable? (Choose two.)
Correct: Fiber-optic cabling supports higher bandwidth than UTP for longer distances. Fiber is immune to EMI and RFI, but costs more, requires more skill to install, and requires more safety precautions.
When the store-and-forward method of switching is in use, what part of the Ethernet frame is used to perform an error check?
Correct: The cyclic redundancy check (CRC) part of the trailer is used to determine if the frame has been modified during transit. If the integrity of the frame is verified, the frame is forwarded. If the integrity of the frame cannot be verified, then the frame is dropped.
Which switching method uses the CRC value in a frame?
Correct: When the store-and-forward switching method is used, the switch receives the complete frame before forwarding it on to the destination. The cyclic redundancy check (CRC) part of the trailer is used to determine if the frame has been modified during transit. In contrast, a cut-through switch forwards the frame once the destination Layer 2 address is read. Two types of cut-through switching methods are fast-forward and fragment-free.
What are two actions performed by a Cisco switch? (Choose two.)
Correct: Important actions that a switch performs are as follows:
Which two statements describe features or functions of the logical link control sublayer in Ethernet standards? (Choose two.)
Correct: Logical link control is implemented in software and enables the data link layer to communicate with the upper layers of the protocol suite. Logical link control is specified in the IEEE 802.2 standard. IEEE 802.3 is a suite of standards that define the different Ethernet types. The MAC (Media Access Control) sublayer is responsible for the placement and retrieval of frames on and off the media. The MAC sublayer is also responsible for adding a header and a trailer to the network layer protocol data unit (PDU).
Open the PT Activity. Perform the tasks in the activity instructions and then answer the question.
Which port does Switch0 use to send frames to the host with the IPv4 address 10.1.1.5?
Correct: Issuing the command ipconfig /all from the PC0 command prompt displays the IPv4 address and MAC address. When the IPv4 address 10.1.1.5 is pinged from PC0, the switch stores the source MAC address (from PC0) along with the port to which PC0 is connected. When the destination reply is received, the switch takes the destination MAC address and compares to MAC addresses stored in the MAC address table. Issuing the show mac-address-table on the PC0 Terminal application displays two dynamic MAC address entries. The MAC address and port entry that does not belong to PC0 must be the MAC address and port of the destination with the IPv4 address 10.1.1.5.
What OSI physical layer term describes the process by which one wave modifies another wave?
Correct: Correct
What OSI physical layer term describes the capacity at which a medium can carry data?
Correct: Correct
What OSI physical layer term describes the capacity at which a medium can carry data?
Correct: Correct
What OSI physical layer term describes the measure of the transfer of bits across a medium over a given period of time?
Correct: Correct
What OSI physical layer term describes the amount of time, including delays, for data to travel from one point to another?
Correct: Correct
What OSI physical layer term describes the amount of time, including delays, for data to travel from one point to another?
Correct: Correct
What OSI physical layer term describes the measure of usable data transferred over a given period of time?
Correct: Correct
What OSI physical layer term describes the physical medium which uses electrical pulses?
Correct: Correct
What OSI physical layer term describes the physical medium that uses the propagation of light?
Correct: Correct
What OSI physical layer term describes the physical medium for microwave transmissions?
Correct: Correct
Which two functions are performed at the MAC sublayer of the OSI data link layer? (Choose two.)
Correct: Correct
Which two functions are performed at the LLC sublayer of the OSI data link layer? (Choose two.)
Correct: Correct
Which two functions are performed at the MAC sublayer of the OSI data link layer? (Choose two.)
Correct: Correct
Which two functions are performed at the MAC sublayer of the OSI data link layer? (Choose two.)
Correct: Correct
Which two functions are performed at the LLC sublayer of the OSI data link layer? (Choose two.)
Correct: Correct
Which two functions are performed at the MAC sublayer of the OSI data link layer? (Choose two.)
Correct: Correct
Which two functions are performed at the LLC sublayer of the OSI data link layer? (Choose two.)
Correct: Correct
Which two functions are performed at the MAC sublayer of the OSI data link layer? (Choose two.)
Correct: Correct
Which two functions are performed at the LLC sublayer of the OSI data link layer? (Choose two.)
Correct: Correct
Which two functions are performed at the MAC sublayer of the OSI data link layer? (Choose two.)
Correct: Correct
What action will occur if a switch receives a frame and does have the source MAC address in the MAC table?
Correct: Correct
What action will occur if a switch receives a frame with the destination MAC address FF:FF:FF:FF:FF:FF?
Correct: Correct
What action will occur if a host receives a frame with a destination MAC address it does not recognize?
Correct: Correct
What action will occur if a switch receives a frame with the destination MAC address 01:00:5E:00:00:D9?
Correct: Correct
What action will occur if a host receives a frame with a destination MAC address of FF:FF:FF:FF:FF:FF?
Correct: Correct
What action will occur if a switch receives a frame and does have the source MAC address in the MAC table?
Correct: Correct
What action will occur if a host receives a frame with a destination MAC address of FF:FF:FF:FF:FF:FF?
Correct: Correct
What action will occur if a switch receives a frame and does have the source MAC address in the MAC table?
Correct: Correct
What action will occur if a host receives a frame with a destination MAC address it does not recognize?
Correct: Correct
What action will occur if a switch receives a frame with the destination MAC address FF:FF:FF:FF:FF:FF?
Correct: Correct
What is a primary role of the Physical layer in transmitting data on the network?
Correct: 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.
With the use of unshielded twisted-pair copper wire in a network, what causes crosstalk within the cable pairs?
Correct: Crosstalk is a type of noise, or interference that occurs when signal transmission on one wire interferes with another wire. When current flows through a wire a magnetic field is produced. The produced magnetic field will interface the signal carried in the adjacent wire.
Refer to the graphic. What type of cabling is shown?
Correct: Network cabling include different types of cables:
Refer to the graphic. What type of cabling is shown?
Correct: Network cabling include different types of cables:
Which three basic parts are common to all frame types supported by the data link layer? (Choose three.)
Correct: The data link protocol is responsible for NIC-to-NIC communications within the same network. Although there are many different data link layer protocols that describe data link layer frames, each frame type has three basic parts:
Which statement is true about the CSMA/CD access method that is used in Ethernet?
Correct: Legacy bus-topology Ethernet LAN uses CSMA/CD as network media access control protocol. It works by detecting a collision in the medium and backing off (after transmitting a jam signal) as necessary. When one host wants to transmit a frame, it listens on the medium to check if the medium is busy. After it senses that no one else is transmitting, the host starts transmitting the frame, it also monitors the current level to detect a collision. If it detects a collision, it transmits a special jam signal so that all other hosts can know there was a collision. The other host will receive this jam signal and stop transmitting. After this, both hosts enter an exponential backoff phase and retry transmission.
What does the term "attenuation" mean in data communication?
Correct: Data is transmitted on copper cables as electrical pulses. A detector in the network interface of a destination device must receive a signal that can be successfully decoded to match the signal sent. However, the farther the signal travels, the more it deteriorates. This is referred to as signal attenuation.
What makes fiber preferable to copper cabling for interconnecting buildings? (Choose three.)
Correct: Optical fiber cable transmits data over longer distances and at higher bandwidths than any other networking media. Unlike copper wires, fiber-optic cable can transmit signals with less attenuation and is completely immune to EMI and RFI.