问答题What field in IP packet is prevent the packet from a route to router forever？

考题阅读下面的短文，回答问题 [When an IP packet arrives at a router, generally the router looks at the destination address of the packet, and forwards the packet to one of its network interfaces. The forwarding decision is usually done by looking up the destination address from another data structure called a forwarding table. The forwarding table is created by the router using the routing table and possible routing policies existing in the router. The router then creates a table where it lists which networks are accessible through which of the routers network interfaces. An IP router looks at every IP packet individually and does the forwarding decision on a packet-by-packet basis. If something changes in the routers routing table, a packet can take a different route from a preceding packet even if it has the same destination.] From the paragraph above，we can see that the router （） a forwarding table according to the routing table and possible routing policies existing in the router. When an IP packet arrives at a router, the （） part of packet is normally checked by the router. An IP router checks every IP Packet individually and makes the forwarding decision based on （）.A．is generating B．generate C．is generated D．generates A．forwarding table B．network interfaces C．routing policies D．destination address A．the destination address and network interfaces B．forwarding table and network interfaces C．the destination address and forward table D．routing policies and routing table

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考题 Router VE1 has just received a packet and needs to route it. What two actions must this router take in order to route incoming packets? (Choose two)A. Inspect the routing table to select the best path to the destination network addresses.B. Validate sources of routing information.C. Inspect the ARP table to verify a legitimate source MAC address for each packet.D. Identify the destination network address of each packet.E. Verify the receipt of routed packets by the next hop router.F. Identify the source network address of each packet.

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考题 A router receives a packet from a neighbor with an MPLS shim header value of 0.What does the router do with this packet?() A. It performs a label pop operation and an IP lookup.B. It performs a label swap operation and an IP lookup.C. It sends an error message toward the egress router.D. It sends an error message toward the ingress router.

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考题 When does the E－series router start monitoring DHCP traffic using the DHCP External function?() A. When the discovery packet enters the router from the DHCP client.B. Only when the offer packet enters the router from the DHCP server.C. When the acknowledge packet enters the router from the DHCP server.D. Only when the discovery packet leaves the router going to the DHCP server.

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考题 A router receives a packet on interface 172.16.45.66／26. The source IP of the packet is 172.16.45.127／26 and the destination is 172.16.46.191／26.How will the router handle the packet?() A. The destination is a host on another subnet, so the router will not forward the packet.B. The destination is a host on the same subnet, so the router will forward the packet.C. The destination is a broadcast address, so the router will not forward the packet.D. The destination is a network address, so the router will forward the packet.

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考题 The following configuration line was added to router R1 Access－list 101 permit ip 10.25.30.00.0.0.255 any What is the effect of this access list configuration?() A.ermit all packet smatching the first three octets of the source address to all destinationsB.permit all packet matching the last octet of the destination address and accept all source addressesC.permit all packet matching the host bits in the source address to all destinationsD.permit all packet from the third subnet of the network address to all destinations

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考题 Refer to the exhibit. What does the (*) represent in the output?() A.Packet is destined for a local interface to the router.B.Packet was translated, but no response was received from the distant device.C.Packet was not translated, because no additional ports are available.D.Packet was translated and fast switched to the destination.

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考题 Anytime a host or a router has an IP datagram to send to another host or router, it has the（　）address of the receiver. This address is obtained from the DNS if the sender is the host or it is found in a routing table if the sender is a router. But the IP data gram must be（　） in a frame to be able to pass through the physical network. This means that the sender needs the （　）address of the receiver. The host or the router sends an ARP query packet. The packet includes the physical and IP addresses of the sender and the IP address of the receiver. Because the sender does not know the physical address of the receiver, the query is（　） over the network.Every host or router on the network receives and processes the ARP query packet, but only the intended recipient recognizes its IP address and sends back an ARP response packet.The response packet contains the recipient's IP and physical addresses. The packet is（请作答此空） directly to the inquirer by using the physical address received in the query packet. A. multicast B. unicast C. broadcast D. multiple unicast

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考题 What is the best description of serialization delay？（）A、the time it takes for a Layer 3 switch or a router to switch a packet from an inbound interface to the queue of the outbound interfaceB、the time it takes for a propagate from source to destinationC、the time it takes to place a frame on the physical medium for transportD、the time a packet resides in the outbound queue of a router

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考题 The following configuration line was added to router R1 Access-list 101 permit ip 10.25.30.00.0.0.255 any What is the effect of this access list configuration?（）A、ermit all packet smatching the first three octets of the source address to all destinationsB、permit all packet matching the last octet of the destination address and accept all source addressesC、permit all packet matching the host bits in the source address to all destinationsD、permit all packet from the third subnet of the network address to all destinations

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考题 What field in IP packet is used for classification by QOS？

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考题 Router R1, a branch router, connects to the Internet using DSL. Some traffic flows through a GRE and IPsec tunnel, over the DSL connection, destined for an Enterprise network. Which of the following answers best describes the router's logic that tells the router, for a given packet, to apply GRE encapsulation to the packet?（）A、When the packet received on the LAN interface is permitted by the ACL listed on the tunnel greacl command under the incoming interfaceB、When routing the packet, matching a route whose outgoing interface is the GRE tunnel interfaceC、When routing the packet, matching a route whose outgoing interface is the IPsec tunnel interfaceD、When permitted by an ACL that was referenced in the associated crypto map

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考题 When an IP packet is Layer 3-switched from a source in one VLAN to a destination in anotherVLAN, which field in a packet will be rewritten? （）A、Layer 2 TTLB、Layer 3 TTLC、Layer 3 source addressD、Layer 3 transport protocolE、Layer 3 destination address

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考题 What best describes processing delay？（）A、the time required from receipt of the incoming frame， until the frame/packet has been queued for transmissionB、the time taken for a single packet to traverse the physical medium from one end to the otherC、the time taken to place a frame on the physical medium for transportD、the time spent for a packet to reside in the output queue of a router

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考题 When an IP packet is Layer 3-switched from a source in one VLAN to a destination in another VLAN,which field in a packet will be rewritten? （）A、Layer 2 TTLB、Layer 3 TTLC、Layer 3 source addressD、Layer 3 transport protocolE、Layer 3 destination address

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考题 Which ERX Edge Router component is responsible for all packet processing and packet forwarding？（）A、I/O adapterB、line moduleC、shared memory fabricD、switch route processor

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考题 A router receives a packet from a neighbor with an MPLS shim header value of 0.What does the router do with this packet?（）A、It performs a label pop operation and an IP lookup.B、It performs a label swap operation and an IP lookup.C、It sends an error message toward the egress router.D、It sends an error message toward the ingress router.

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考题 Which statement correctly describes the disabling of IP TTL propagation in an MPLS network？（）A、The TTL field from the IP packet is copied into the TTL field of the MPLS label header at the ingress edge LSRB、TTL propagation cannot be disabled in an MPLS domainC、TTL propagation is only disabled on the ingress edge LSRD、The TTL field of the MPLS label header is set to 255E、The TTL field of the IP packet is set to 0

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考题 What field in IP packet is prevent the packet from a route to router forever？

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考题 When does the E-series router start monitoring DHCP traffic using the DHCP External function?（）A、When the discovery packet enters the router from the DHCP client.B、Only when the offer packet enters the router from the DHCP server.C、When the acknowledge packet enters the router from the DHCP server.D、Only when the discovery packet leaves the router going to the DHCP server.