●The network layer provides services to the transport layer.It can be based on either（71）.In both cases,its main job is（请作答此空）packets from the source to the destination.In network layer,subnets can easily become congested，increasing the delay and（73）for packets.Network designers attempt to avoid congestion by proper design.Techniques include（74）policy,caching,flow control,and more.The next step beyond just dealing with congestion is to actually try to achieve a promised quality of service.The methods that can be used for this include buffering at the client,traffic shaping,resource（75），and admission control.Approaches that have been designed for good quality of service include integrated services（including RSVP）,differentiated services，and MPLS.A.dealing withB.routingC.sendingD.receiving
●The network layer provides services to the transport layer.It can be based on either（71）.In both cases,its main job is（请作答此空）packets from the source to the destination.In network layer,subnets can easily become congested，increasing the delay and（73）for packets.Network designers attempt to avoid congestion by proper design.Techniques include（74）policy,caching,flow control,and more.The next step beyond just dealing with congestion is to actually try to achieve a promised quality of service.The methods that can be used for this include buffering at the client,traffic shaping,resource（75），and admission control.Approaches that have been designed for good quality of service include integrated services（including RSVP）,differentiated services，and MPLS.
A.dealing with
B.routing
C.sending
D.receiving
B.routing
C.sending
D.receiving
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The network layer provides services to the transport layer．It can be based on either (1)．In both cases，its main job is (2) packets from the source to the destination．In network layer，subnets can easily become congested，increasing the delay and (3).for packets．Network designers attempt to avoid congestion by proper design．Techniques include (4) policy，caching，flowcontrol，and more．The next step beyond just dealing with congestion is to actually try to achieve a promised quality of service．The methods that can be used for this include buffering at the client，traffic shaping，resource (5)，and admission control．Approaches that have been designed for good quality of service include integrated services(including RSVP) ，differentiated services， and MPLS．(1)A．virtual circuits or datagramsB．TCP or UDPC．TCP or IPD．IP or ARP
●Networks can be interconnected by different devices．In the physical layer，networks can be connected by (66) or Hubs，which just move the bits from one network to an identical network．One layer up we find bridgas and swiehes,which operate at data link layer．They can accept (67) ，examine the MAC address，and forward the frames to a different network while doing minor protocol translation in the process．In the network layer，we have routers that can connect two netwoks．If two networks have (68) network layer，the router may be able to translate between the packet formats．In the transport layer we find transport gateway，which can interface between the two transport connections．Finally，in the application layer，application gateways translate message (69) ．As an example，gateways between Internet e-mail and X．400 e-mail must (70) the e-mail message and change various header fields．(66) A．reapersB．relaysC．connectsD．modems(67) A．framesB．bytesC．packagesD．cells(68) A．specialB．dependentC．similarD．dissimilar(69) A．syntaxB．semanticsC．languagesD．format(70) A．analyzeB．pairsC．deleteD．create
The network layer provides services to the transport layer．It call be based on either virtual circuits or datagrams．In both cases，its main job is（ ）packets from the source to the destination． A．dealing with B．sending C．routing D．receiving
In the open systems interconnection (OSI) reference model, "layer" means one of seven conceptually complete,(71) arranged groups of services, functions, and protocols, that extend across all open systems.Application layer provides means for the application(72) to access the OSI environment. Presentation layer provides for the selection of a common syntax for representing data.(73) layer provides the means necessary for cooperating presentation entities to organize and synchronize their dialog and to manage their data exchange. Transport layer provides a reliable end-to-end data transfer service. Network layer provides for the entities in the transport layer the means for transferring blocks of data, by(74) and switching through the network between the open systems in which those entities reside. Data link layer provides services to transfer data between network layer entities. Physical layer provides the mechanical, electrical, functional, and procedural means to establish, maintain and(75) physical connections for transfer of bits over a transmission medium.A．ranklyB．levellyC．layeredD．hierarchically
Networks can be interconnected by different devices in the physical layer networks can be connected by (71) or hubs．which just move the bits from one network to an identical network．One layer up we find bridges and switches which operate at data link layer．They can accept (72) ，examine the MAC address and forward the frames to a different network while doing minor protocol translation in the process in me network layer，we have routers that can connect two networks，If two networks have (73) network layer，the router may be able to translate betweenthe packer formats．In the transport layer we find transport gateway，which can interface between two transport connections Finally，in the application layer，application gateways translate message (74) ．As an example，gateways between Internet e-mail and X，400 e-mail must (75) thee-mail message and change various header fields．(68)A．reapersB．relaysC．packagesD．modems
Networks can be interconnected by different devices. In the physical layer, networks can be connected by(66)or hubs, which just move the bits from one network to an identical network. One layer up we find bridges and switches, which operate at data link layer. They can accept(67), examine the MAC address, and forward the frames to a different network while doing minor protocol translation in the process. In the network layer, we have routers that can connect two networks. If two networks have(68)network layer, the router may be able to translate between the packet formats. In the transport layer we fmd transport gateway, which can interface between two transport connections. Finally, in the application layer, application gateways translate message(69). As an example, gateways between Internet e-mail and X.400 e-mail must(70)the e-mail message and change various header fields.A．repeatersB．relaysC．connectorsD．modems
● TCP/IP communication protocol contains four layers. From bottom to top, the four layers are __(71)__.（71）A．network interface layer, internet layer, transport layer and application layerB．internet layer, network interface layer, transport layer and application layerC．network interface layer, transport layer, network interface layer and application layerD．application layer, transport layer, internet layer and network interface layer
TCP/IP communication protocol contains four layers． From bottom to top, the four layers are __（71）__．A.network interface layer, internet layer, transport layer and application layerB.internet layer, network interface layer, transport layer and application layerC.network interface layer, transport layer, network interface layer and application layerD.application layer, transport layer, internet layer and network interface layer
Together with the network layer,the transport layer is the heart of the protocol（ ）The network layer provides end-to-end（ ） delivery using datagrams or virtual circuits.The transport layer builds on the network layer to provide data transport from a process on a（ ）machine to a process on a destination machine with a desired level of reliability that is independent of the physical （ ） currently in use.It provides the abstractions that applications nedd to use the network..Without the（ ） layer,the whole concept of layered protocols would make little sense.A.transport B.network C.hierarchy D.service A.packet B.data C.command D.record A.connection B.terminal C.source D.destination A.traffic B.connection C.lines D.networks A.network B.transport C.link D.physical
Which two of these are characteristics of MPLS VPNs?() A. Layer 3 MPLS VPNs can forward only IP packetsB. Layer 2 MPLS VPNs can forward any network protocolC. MPLS label paths are automatically formed based on Layer 2 framesD. Layer 3 MPLS VPNs can forward any network protocol based on Layer 2 framesE. In Layer 2 MPLS VPNS, the service provider controls the customer Layer 3 policies
根据下面的文字资料回答 71～75 题 connected by（ 1 ）or Hubs,which just move the bits from one network to an identical network. One layer up we find bridgas and swiehes,which operate at data link layer. They can accept （ 2 ） , examine the MAC address, and forward the frames to a different network while doing minor protocol translation in the process. In the network layer,we have touters that can connect two netwoks. If two networks have（ 3 ）network layer,the router may be able to translate between the packet formats. In the transport layer we find transport gateway, which cart interface between the two transport connections. Finally, in the application layer, application gateways translate message（ 4 ）. As an example,gateways between Internet e-mail and X.400 e-mail must （ 5 ）the e-mail message and change various header fields.第6题：文中（ 1 ）处正确的答案是（ ）。A．reapersB．relaysC．connectsD．modems
TCP/IP communication protocol contains four layers. From bottom to top, the four layers are （ ） .A.network interface layer—internet layer—transport layer—application layerB.internet layer —network interface layer—transport layer—application layerC.network interface layer—transport layer —network interface layer—application layerD.application layer—transport layer —internet layer—network interface layer
Networks can be interconnected by different devices in the physical layer networks can be connected by（ ）_or hubs.which just move the bits from one network to an identical network.One layer up we find bridges and switches which operate at data link layer.They can accept（ ）examine the MAC address and forward the frames to a different network while doing minor protocol translation in the process in me network layer,we have routers that can connect two networks,If two networks have（ ）network layer,the router may be able to translate between the packer formats.In the transport layer we find transport gateway,which can interface between two transport connections Finally,in the application layer,application gateways translate message（请作答此空）.As an example,gateways between Internet e-mail and X.400 e-mail must（ ）the e-mail message and change various header fields.A.syntaxB.semanticsC.languageD.format
TCP/IP（ ）layer protocols provide services to the application（ ）running on a computer.The application layer does not define the application itself,but rather it defines（ ）that applications need--like the ability to transfer a file in the case of HTTP.In short,the application layer provides an（ ）between software running on a computer and the network itself.The TCP/IP application layer includes a relatively large number of protocols,with HTTP being only one of those.The TCP/IP（请作答此空）layer consists of two main protocol options--the Transmission Control Protocol（TCP）and the User Datagram Protocol（UDP）.A.applicationB.sessionC.physicalD.transport
TCP/IP （ ）layer protocols provide services to the application（ ）running on a computer. The application layer does not define the application itself, but rather it defines（请作答此空）that applications need--like the ability to transfer a file in the case of HTTP. In short, the application layer provides an（ ）between software running on a computer and the network itself. The TCP/IP application layer includes a relatively large number of protocols, with HTTP being only one of those. The TCP/IP（ ）layer consists of two main protocol options--the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP).A.servicesB.processesC.applicationsD.address
TCP/IP （请作答此空）layer protocols provide services to the application（ ）running on a computer. The application layer does not define the application itself, but rather it defines（ ）that applications need--like the ability to transfer a file in the case of HTTP. In short, the application layer provides an（ ）between software running on a computer and the network itself. The TCP/IP application layer includes a relatively large number of protocols, with HTTP being only one of those. The TCP/IP（ ）layer consists of two main protocol options--the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP).A.applicationB.transportC.linkD.network
Together with the network layer,the transport layer is the heart of the protocol ( 请作答此空).The network layer provides end-to-end () delivery using datagrams or virtual circuits.The transport layer builds on the network layer to provide data transport from a process on a () machine to a process on a destination machine with a desired level of reliability that is independent of the physical () currently in use.It provides the abstractions that applications nedd to use the network..Without the () layer,the whole concept of layered protocols would make little sense.A.transportB.networkC.hierarchyD.service
IPsec, also known as the internet Protocol ( ) , defines the architecture for security services for IP network traffic IPsec describes the framework for providing security a the IP layer, as well as the suite of protocols designed to provide that security: through_ ( )_ and encryption of IP network packets. IPec can be used 10 protect network data, for example, by setting up circuits using IPsec ( ), in which all data being sent between two endpoints is encrypted, as with a Virtual (请作答此空) Network connection ;for encrypting application layer data ;and for providing security for routers sending routing data across the public internet. Internet traffic can also be secured from host to host without the use of IPsec, for example by encryption at the ( ) layer with HTTP Secure (TTPS)or an the transport layer wit the Transport Layer Security (TLS)protocol.A.pubic]B.private]C.personalD.proper
●The network layer provides services to the transport layer.It can be based on either（请作答此空）.In both cases,its main job is（72）packets from the source to the destination.In network layer,subnets can easily become congested，increasing the delay and（73）for packets.Network designers attempt to avoid congestion by proper design.Techniques include（74）policy,caching,flow control,and more.The next step beyond just dealing with congestion is to actually try to achieve a promised quality of service.The methods that can be used for this include buffering at the client,traffic shaping,resource（75），and admission control.Approaches that have been designed for good quality of service include integrated services（including RSVP）,differentiated services，and MPLS.A.virtual circuits or datagramsB.TCP or UDPC.TCP or IPD.IP or ARP
●The network layer provides services to the transport layer.It can be based on either（71）.In both cases,its main job is（72）packets from the source to the destination.In network layer,subnets can easily become congested，increasing the delay and（请作答此空）for packets.Network designers attempt to avoid congestion by proper design.Techniques include（74）policy,caching,flow control,and more.The next step beyond just dealing with congestion is to actually try to achieve a promised quality of service.The methods that can be used for this include buffering at the client,traffic shaping,resource（75），and admission control.Approaches that have been designed for good quality of service include integrated services（including RSVP）,differentiated services，and MPLS.A.lowering the throughputB.lowering the correctnessC.lowering the effectivenessD.lowering the preciseness
Which of the following correctly describe steps in the OSI data encapsulation process?（）A、The transport layer divides a data stream into segments and may add reliability and flow control information.B、The data link layer adds physical source and destination addresses and an FCS to the segment.C、Packets are created when the network layer encapsulates a frame with source and destination host addresses and protocol-related control information.D、Packets are created when the network layer adds Layer 3 addresses and control information to a segment.E、The presentation layer translates bits into voltages for transmission across the physical link.
Which of the following correctly describe steps in the OSI data encapsulation process?（）A、Transport layer divides a data stream into segments adds reliability flow control informationB、Data link layer adds physical source destination address an FCS to the segmentC、Packets are created when the network layer encapsulate a frame with source destination host address protocol related control informationD、Packets are created when the network layers adds layers 3 address control information to a segmentE、The presentation layer translated bits into bits into voltages for transmission across the physical link
Which three practices are important to the implementation of a DiffServ QoS architecture？（）A、 Because services are allocated throughout the network before the transmission of data begins， traffic classes can be guaranteed QoS services.B、 Traffic classes are marked with Layer 2 markings to allow for more granularity in identifying traffic classes.C、 Traffic classes are marked with Layer 3 markings to allow them to traverse different network types without loss of QoS information.D、 Traffic classes allow networks to provide proper QoS treatment of packets without applications having to request services.E、 Based upon the network capabilities， QoS markings are placed on packets as needed throughout the network to allow for proper QoS treatment of packets.F、 QoS markings are placed on packets as close to the network edge as possible to allow distribution and core devices to determine QoS actions as quickly as possible.
Which two of these are characteristics of MPLS VPNs？ （）A、 Layer 3 MPLS VPNs can forward only IP packetsB、 Layer 2 MPLS VPNs can forward any network protocolC、 MPL S label paths are automatically formed based on Layer 2 framesD、 Layer 3 MPLS VPNs can forward any network protocol based on Layer 2 framesE、 In Layer 2 MPLS VPNS， the service provider controls the customer Layer 3 policies
Which three statements are true about Cisco IOS Firewall？（）A、It can be configured to block Java traffic.B、It can be configured to detect and prevent SYN-flooding denial-of-service （DoS） network attacks.C、It can only examine network layer and transport layer information.D、It can only examine transport layer and application layer information.E、The inspection rules can be used to set timeout values for specified protocols.F、The ip inspect cbac-name command must be configured in global configuration mode.
单选题A layer 3 switch can move packets between subnets based on which of the following criteria?（）A802.1q tagBPortCApplicationDIP address
多选题Which two of these are characteristics of MPLS VPNs?（）ALayer 3 MPLS VPNs can forward only IP packetsBLayer 2 MPLS VPNs can forward any network protocolCMPLS label paths are automatically formed based on Layer 2 framesDLayer 3 MPLS VPNs can forward any network protocol based on Layer 2 framesEIn Layer 2 MPLS VPNS, the service provider controls the customer Layer 3 policies