01. At which two layers of the OSI model does a WAN operate? (Choose two.)
- Physical Layer
- Data Link Layer
- Network Layer
- Transport Layer
- Presentation Layer
- Application Layer
02. Which three WAN devices can be found in the cloud? (Choose three.)
- ATM switches
- core routers
- CSU/DSU
- Ethernet switches
- Frame Relay switches
- Repeaters
- core router
- access server
- Frame Relay switch
- ATM switch
- Time Division Multiplexing (TDM)
- metro Ethernet
- Integrated Services Digital Network (ISDN)
- Public Switched Telephone Network (PSTN)
- CIR
- DLCI
- DSLAM
- PVC
- SPID
- 53-byte cells
- ATM
- ISDN
- Frame Relay
- metro Ethernet
- low cost
- availability
- traffic encryption
- available bandwidth
- support for voice and video
- cell
- DLCI
- circuit switching
- packet switching
- data bearer channels
- time-division multiplexing
- smaller cells
- number of subscribers
- committed information rate
- distance from the central office of the provider
- PVCs
- DLCIs
- tunnels
- dedicated Layer 2 links
- ATM
- ISDN
- analog dialup
- T1 Leased Line
- CSU/DSU
- Frame Relay switch
- ISDN switch
- modem
- PBX switch
- DLCI
- DTE
- DCE
- BRI
- PRI
14. Which switching type will allow the communication devices in the provider network to be shared and only allocated to an individual subscriber during data transfer?
- circuit-switched
- dedicated switched lines
- frame-switched
- packet-switched
- X.25
- DSL
- ATM
- ISDN BRI
- ISDN PRI
- modem
- router
- CSU/DSU
- ISDN switch
- Ethernet switch
- The purpose of the access layer is to provide very high bandwidth communications between network devices.
- Most security screening to prevent unauthorized entry to the network happens at the core layer.
- Untrusted external connections are segmented from the rest of the network at all three levels.
- The distribution layer aggregates WAN connections at the edge of the campus.
- Normally the CSU/DSU is the designated demarcation point for the service provider but not the customer.
- The segment between the demarcation point and the central office is known as the “last mile.”
- The local loop is the segment between the CSU/DSU and the serial port on a router.
- Putting data on the local loop is the responsibility of the DTE.
- WANs generally support higher bandwidth than LANs support.
- A WAN link typically traverses shorter geographic distances than a LAN link traverses.
- A WAN often relies on the services of carriers, such as telephone or cable companies, but a LAN does not.
- All WAN implementations generally use the same Layer 2 protocol but there are many accepted LAN Layer 2 protocols in use.
- Routing protocols are incompatible with this function.
- It restricts the communication sent to voice traffic only.
- A telephone must be used to initially start transferring data.
- Data cannot be transferred until a circuit has been established.
- ATM differs from other WAN protocols in that it uses variably sized packets.
- Most WAN protocols use HDLC or a variant of HDLC as a framing mechanism.
- The frame header consists of the frame check sequence and cyclic redundancy check.
- ISDN differs from Frame Relay, HDLC, and ATM in that it is packet-switched rather than circuit-switched technology.
- Packet-switched networks are less susceptible to jitter than circuit-switched networks are.
- Packet-switched networks can efficiently use multiple routes inside a service provider network.
- Packet-switched networks do not require an expensive permanent connection to each endpoint.
- Packet-switched networks usually experience lower latency than circuit-switched networks experience.
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