CCNA - OSI, Layer, WAN, LAN

CCNA - OSI, Layer, WAN, LAN


What functions do routers perform in a network? (Choose two.)
在網路層，路由器主要扮演什麼功能？
A. packet switching
封包交換
B. access layer security
C. path selection
路徑選擇
D. VLAN membership assignment
VLAN 成員分配
E. bridging between LAN segments
F. microsegmentation of broadcast domains

Answer: AD

At which layers of the OSI model do WANs operate? (Choose two.)
A. application layer
B. session layer
C. transport layer
D. network layer
E. datalink layer
F. physical layer

Answer: EF
WAN 是工作在 Layer 1 和 Layer 2 的
例如常用的 Frame-relay, ATM 等都是工作在 OSI 的 Layer 2

Which of the following correctly describe steps in the OSI data encapsulation process? (Choose two.)
下面哪些正確描述了OSI 資料封裝過程的步驟
A. The transport layer divides a data stream into segments and may add reliability and flow control information.
傳輸層將資料流分割成資料段並可能增加可靠性以及流動控制訊息
B. The data link layer adds physical source and destination addresses and an FCS to the segment.
資料連結層增加源地址和目標地址，同時增加訊框檢查序列到資料段中
C. Packets are created when the network layer encapsulates a frame with source and destination host addresses and protocol‐related control information.
當網路層封裝包括源地址，目標主機地址和有關協議的控制訊息的訊框時，封包被產生
D. Packets are created when the network layer adds Layer 3 addresses and control information to a segment.
當網路層增加 Layer 3地址和控制時封包被產生
E. The presentation layer translates bits into voltages for transmission across the physical link.
表示層將比特轉化成電壓通過實體層

Answer: AD

At which layers of the OSI model do WANs operate? (Choose two.)
OSI 模型中哪層是對 WANs 做操作的？
A. application layer 應用層
B. session layer 會話層
C. transport layer傳輸層
D. network layer 網路層
E. datalink layer 資料連結層
F. physical layer 實體層

Answer: EF

What are two advantages of Layer 2 Ethernet switches over hubs? (Choose two.)
相對於集線器來說，Layer 2 Ethernet 交換器有哪兩個優點
A. decreasing the number of collision domains
降低衝突域的數量
B. filtering frames based on MAC addresses
過濾基於 MAC 地址的資料訊框
C. allowing simultaneous frame transmissions
允許同時存在的訊框傳輸
D. increasing the size of broadcast domains
增加廣播域的大小
E. increasing the maximum length of UTP cabling between devices
增加設備之間 UTP纜的最大長度

Answer: BC

For what two purposes does the Ethernet protocol use physical addresses? (Choose two.)
Ethernet 協議中使用physical 地址是為了哪兩個目的？
A. to uniquely identify devices at Layer 2
為了在Layer 2中做獨一無二的設備標識
B. to allow communication with devices on a different network
為了允許在不同網路上的設備之間的通信
C. to differentiate a Layer 2 frame from a Layer 3 packet
為了從 Layer 3 封包中區分出 Layer 2 資料訊框
D. to establish a priority system to determine which device gets to transmit first
為了建立一個優先級系統來決定哪個設備首先來傳輸
E. to allow communication between different devices on the same network
為了允許在同一網路內的不同設備之間的通信
F. to allow detection of a remote device when its physical address is unknown
當一個設備的physical 地址不清楚的情況下，允許遠程設備的檢測

Answer: AE

As a frame leaves a Layer 3 device, the Layer 2 encapsulation information is changed from what it was when it entered the device. For what two reasons can this happen? (Choose two.)
當一訊框資料離開三層設備，當它進入設備時二層的封裝訊息被改變。請問由什麼原因引起？
A. The data is moving from 10BASE‐TX to 100BASE‐TX.
資料由 10BASE-TX 移動到 100BASE-TX
B. The WAN encapsulation type has changed.
廣域網的封裝類型被改變
C. The data format has changed from analog to digital.
從模擬到數字資料格式被改變
D. The source and destination hosts are in the same subnet.
源地址和目的地址主機在同一子網
E. The source and destination MAC addresses have changed.
源地址和目的地址的 MAC 地址被改變

Answer: BE

Which three Layer 2 encapsulation types would be used on a WAN rather than a LAN?
(Choose three.)
相對於區域網來說，在廣域網中哪三種 2 層封裝類型將被使用？
A. HDLC
B. Ethernet
C. Token Ring
D. PPP
E. FDDI
F. Frame Relay

Answer: ADF

Which three Layer 2 encapsulation types would be used on a WAN rather than a LAN? (Choose three.)
A. HDLC
B. Ethernet
C. Token Ring
D. PPP
E. FDDI
F. Frame Relay

Answer: ADF
Layer 2 的封裝協議
HDLC,PPP,FRAME-RELAY都是用在廣域網上面

The network administrator has discovered that the power supply has failed on a switch in the company LAN and that the switch has stopped functioning. It has been replaced with a Cisco Catalyst 2950 series switch. What must be done to ensure that this new switch becomes the root bridge on the network?
一管理員發現屬於公司 LAN 上的交換器的電源出現故障導致不能工作。用一思科 2950 系列的交換器替換。必須對該新的交換器做哪些設定確保成為網路的Root Bridge？
A. Lower the bridge priority number.
降低Root Bridge的優先級
B. Change the MAC address of the switch.
改變該交換器的 MAC 地址
C. Increase the VTP revision number for the domain.
對這區域增加 VTP 的修訂號。
D. Lower the root path cost on the switch ports.
在交換器port上降低根路徑的花費。
E. Assign the switch an IP address with the lowest value.
以最低值在該交換器上分配一 IP 地址。

Answer: A

Which of the following describes the roles of devices in a WAN? (Choose three.)
以下選項中哪些描述了廣域網中設備的作用？
A. A CSU/DSU terminates a digital local loop.
CSU/DSU終止一個數位local loop
B. A modem terminates a digital local loop.
modem終止一個數位local loop
C. A CSU/DSU terminates an analog local loop.
CSU/DSU 終止一個類比local loop
D. A modem terminates an analog local loop.
modem終止一個類比local loop
E. A router is commonly considered a DTE device.
路由器通常被認為是資料終端設備
A router is commonly considered a DCE device.
路由器通常被認為是資料通信設備

Answer: ADE