SPCORE question of the day
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Which three conditions can occur when metering traffic using a dual token bucket traffic policing QoS mechanism on Cisco routers?
A. conform
B. exceed
C. matched
D. violate
E. pass
F. burst
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53 Comments sorted by
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What is the correct formula for determining the CIR?
A. CIR = (Bc+Be)/Tc
B. CIR = Bc/Tc
C. CIR = Tc/(Bc+Be)
D. CIR = Bc x Tc
E. CIR = Tc/Bc
F. CIR = Bc + Be
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DS-TE implementations on Cisco routers support which bandwidth pool(s) and class type(s)?
A. global pool and subpool
B. subpool only
C. class-type 1 only
D. global pool only
E. class-type 0 and class-type 1
F. class-type 0 only
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Which field in the MPLS shim header is used to support different QoS markings?
A. S
B. DSCP
C. Label
D. IP precedence
E. EXP
F. TOS
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On a Cisco IOS XR router, which mechanism protects the router resources by filtering and policing the packets flows that are destined to the router that is based on defined flow-type rates?
A. Committed Access Rate
B. ACL
C. Management Plane Protection
D. NetFlow
E. Control Plane Policing
F. LLQ
G. LPTS
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When configuring LLQ (strict priority queue) on a traffic class using the Cisco IOS XR priority command on a Cisco ASR9K router, which additional QoS command is required for this traffic class?
A. shape
B. police
C. bandwidth
D. random-detect
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On the Cisco ASR9K router, when using the bandwidth command to specify the minimum guaranteed bandwidth to be allocated for a specific class of traffic, what will be used as the queuing algorithm?
A. FIFO
B. priority queuing
C. custom queuing
D. CBWFQ
E. WFQ
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When implementing MPLS DS-TE on Cisco IOS XR routers, all aggregate Cisco MPLS TE traffic is mapped to which class type by default?
A. class-type 2 (bandwidth priority)
B. class-type class-default (bandwidth best-effort)
C. class-type 0 (bandwidth global pool)
D. class-type 1 (bandwidth subpool)
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On the Cisco IOS XR, which MQC configuration is different than on the Cisco IOS and IOS XE?
A. On the Cisco IOS XR, WRED can only be applied in the output direction.
B. On the Cisco IOS XR, LLQ can be applied in the input or output direction.
C. On the Cisco IOS XR, LLQ can use up to four priority queues: level 1, level 2, level 3, and level 4.
D. On the Cisco IOS XR, marking can only be applied in the input direction.
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On Cisco routers, how is hierarchical QoS implemented?
A. Use the policy-map command within a service-policy to implement nested policy-maps.
B. Within the child policy, reference another parent policy using the policy-map command.
C. Within the parent policy-map, reference another child policy-map using the service-policy command.
D. Within the parent policy, reference another child policy using the policy-map command.
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Refer to the Cisco IOS XR policy-map configuration exhibit.
policy-map test
!
class one
priority level 1
!
class two
priority level 2
!
class three
bandwidth percent 60
!
interface GigabitEthernet0/0/0/2
service-policy output test
!
What is wrong with the policy-map configuration?
A. missing the bandwidth command under class one and class two
B. missing the priority percent command under class one and class two
C. missing the police command under class three
D. missing the police command under class one and class two
E. missing the priority bandwidth command under class one and class two
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When configuring class-based WRED on Cisco routers, which WRED parameter is not user configurable on a Cisco IOS XR but is user configurable on a Cisco IOS and IOS XE?
A. the maximum threshold
B. the minimum threshold
C. the ingress or egress direction where the class-based WRED policy will be applied
D. the mark probability denominator
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Which of the following three statements are correct regarding IPv6 QoS?
A. DS-TE is not supported by IPv6.
B. Per-hop behavior in IPv6 networks is based on EXP bits.
C. A 20-bit flow label field enables per-flow processing.
D. IPv6 QoS features are configured using the modular QoS CLI on Cisco routers.
E. The traffic class field in the IPv6 header can be used to set specific precedence or DSCP values.
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With unmanaged CE routers, at which point in the service provider network is the QoS trust boundary, and what is required at the trust boundary?
A. between the customer network and the CE router ingress and applying the required egress QoS policy on the CE router
B. between the PE and P router and trusting the QoS markings from the CE router and applying the required QoS mechanisms based on the customer QoS markings
C. between the CE and PE router and mapping of the customer traffic classes into the service provider traffic classes at the PE router ingress
D. between the PE and the P router and mapping of the customer traffic classes into the service provider traffic classes at the P router ingress
E. between the CE and PE router and trusting the QoS markings from the CE router and applying the required QoS mechanisms based on the customer QoS markings
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On the Cisco IOS XR, when using the match protocol command within a class-map to classify traffic, you noticed that the match protocol option on the Cisco IOS XR shows much fewer protocol options than on the Cisco IOS or IOS XE, like there is no option such as the match protocol yahoo-messenger command on the Cisco IOS XR. Why is this?
A. because NBAR is not supported on the Cisco IOS XR
B. because when defining the class-map, the class-map type should be set to type inspect: class-map type inspect class-map-name command
C. because the Cisco IOS XR router does not have the correct software packages installed
D. because flexible packet matching has not been enabled on the Cisco IOS XR router
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Within the service provider core network, which two QoS mechanisms are typically deployed on the P routers?
A. traffic shaping
B. traffic policing and remarking
C. WRED
D. link fragmentation and interleaving
E. traffic classification and markings
F. LLQ
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Which three steps are required to configure QPPB on Cisco IOS XR routers?
A. Define a QPPB route policy to match the customer IP precedence or qos-group markings, then set the BGP community
B. Enable QPPB on an interface using the ipv4 bgp policy propagation input ip-precedence|qos-group destination|source command
C. Define a QPPB route policy to match the customer routes, then set the IP precedence or qos-group
D. Apply a QPPB route policy to the BGP neighbor using the route-policy command
E. Enable QPPB on an interface using the ipv4 bgp policy propagation output ip-precedence|qos-group destination|source command
F. Apply a QPPB route policy to the BGP process using the table-policy command
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The Cisco IOS and IOS XE qos pre-classify command allows which kind of packet classification on IP packets that are encapsulated with GRE and IPsec?
A. allows for packets to be classified based on the packet payload after packet encryption
B. allows for packets to be classified based on the ToS byte values before packet encryption
C. allows for packets to be classified based on the packet payload before packet encryption
D. allows for packets to be classified based on the packet header parameters other than the ToS byte values after packet encryption
E. allows for packets to be classified based on the ToS byte values after packet encryption
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Which are typical class-based marking policies that are implemented on service provider IP NGN PE routers?
A. On the PE ingress, classify the customer traffic and then mark with qos-group. On the PE egress, classify based on the qos-group and then mark with mpls exp.
B. On the PE ingress, trust the customer QoS markings. On the PE egress, classify based on the customer QoS markings and then mark with mpls exp.
C. On the PE ingress, classify the customer traffic and then mark with mpls exp. On the PE egress, classify based on the mpls exp and then mark with qos-group.
D. On the PE ingress, trust the customer QoS markings. On the PE egress, classify based on the customer QoS markings and then mark with qos-group.
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Which item is not available to be used for QoS classification in Cisco IOS XR?
A. MAC SA
B. VLAN
C. inner EXP
D. QoS-group
E. protocol
F. discard-class
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Which statement is correct regarding the default MPLS TTL behavior?
A. When an ingress edge LSR receives an IP packet, it will decrement the IP TTL field by 1; then it will copy the decremented IP TTL field into the MPLS Label TTL field.
B. When an ingress edge LSR receives an IP packet, it will copy the IP TTL field into the MPLS Label TTL field first; then it will only decrement the MPLS Label TTL field by 1.
C. When an ingress edge LSR receives an IP packet, it will decrement the IP TTL field by 1; then it will set the MPLS Label TTL field to 255.
D. When an ingress edge LSR receives an IP packet, it will copy the IP TTL field into the MPLS Label TTL field first; then it will only decrement the IP TTL field by 1.
E. When an ingress edge LSR receives an IP packet, it will just copy the IP TTL field into the MPLS Label TTL field.
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Which three statements are correct regarding ping mpls command operations?
A. They are used to test for a broken LSP.
B. They use a 127/8 address as the destination address in the MPLS echo request packet.
C. They use ICMP echo request and ICMP echo reply packets.
D. If there is a broken LSP, instead of using label switching, the packet can still be forwarded based on the destination IP address in the mpls ping echo request packet.
E. MPLS OAM has to be enabled on the router using the mpls oam command.
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What are the four fields inside the MPLS shim header?
A. Type
B. Label
C. S
D. TTL
E. FCS
F. Version
G. EXP
H. Length
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Which two of the following statements are correct regarding LSPs?
A. Each LSP is bidirectional, that is, packets traveling in the opposite direction use the same LSP.
B. An LSP is created for every routing protocol entry.
C. The FIB is used to forward MPLS-labeled packets down an LSP.
D. An IGP is used to populate routing tables in all routers in an MPLS domain.
E. LDP is used to propagate labels and build LSPs.
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Which four pieces of information are stored for each prefix in the LFIB?
A. next-hop IP address
B. Layer 2 header rewrite information
C. outgoing label
D. outgoing interface
E. incoming interface
F. local label
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Which three network services can be implemented using MPLS within the service provider IP NGN core?
A. IntServ traffic engineering tunnels
B. Layer 2 VPNs
C. Layer 3 VPNs
D. encrypted LSPs
E. traffic engineering
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LDP session protection uses which one to maintain the LDP session between LDP neighbors?
A. LDP-IGP synchronization
B. BFD
C. backup-targeted LDP hellos
D. LDP NSR
E. LDP NSF
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You are tasked to enable LDP on many of the interfaces on the Cisco CRS-3 router, and because there are many interfaces that need to have LDP enabled, you mistakenly did not enable LDP on all the required interfaces. To prevent this issue from happening again in the future, what could you do the next time you need to enable LDP on many interfaces?
A. use the interface all command under the MPLS LDP process
B. use the mpls ldp sync command under the IGP routing precess
C. use the discovery command under the MPLS LDP process
D. use the mpls ldp auto-config command under the IGP routing process
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Which two statements are correct in describing ISP environments that are running IP/MPLS in the core network?
A. The PE and P routers run LDP to learn the labels for reaching the BGP next-hop addresses.
B. The BGP next hops point to the PE routers, and only the PE routers are required to run BGP.
C. A full mesh of IBGP sessions are required between all of the PE and P routers to ensure proper packets forwarding.
D. On the PE routers, each BGP route must use a unique label to reach the BGP next hop.
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When troubleshooting LDP operations on the Cisco IOS and IOS XE routers, what is one of the first things that should be verified?
A. check if the ip cef command has been enabled
B. if running OSPF as the IGP, ensure that OSPFv3 has been enabled
C. verify in the running configurations that all of the required LDP interfaces are defined under the mpls ldp command configuration mode
D. verify if there are any access lists that are denying TCP and UDP port 464 packets
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Referring to the Cisco IOS XR configuration exhibit,
mpls ldp
label
advertise
disable
for test1 to test2
!
ipv4 access-list test2
10 permit ipv4 any any
ipv4 access-list test1
10 permit ipv4 host 10.1.1.1 any
which labels will be advertised by the router with this configuration?
A. Only the label for 10.1.1.1/32 will be advertised to all the LDP peers.
B. No labels will be advertised to any LDP peers.
C. Labels for all prefixes will be advertised to the 10.1.1.1 LDP peer.
D. Labels for all prefixes will be advertised to all the LDP peers.
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What is the term that is used for the label that an LSR assigns and distributes to other LSRs in MPLS?
A. Aggregate
B. Explicit
C. Remote
D. Explicit Null
E. Local
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Which Cisco IOS XR high-availability feature is used to prevent routes from being used before LDP converges?
A. IGP session protection
B. BFD
C. LDP session protection
D. LDP-IGP synchronization
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Which Cisco IOS XR command should be used in order to enable LDP-IGP synchronization for the ISIS IGP protocol?
A. RP/0/RSP0/CPU0:R1(config-ldp)#isis ldp sync
B. RP/0/RSP0/CPU0:R1(config-isis-if-af)#mpls ldp sync
C. RP/0/RSP0/CPU0:R1(config-isis)#mpls ldp sync
D. LDP-IGP synchronization is not supported for the ISIS IGP protocol on Cisco IOS XR platforms
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Referring to the Cisco IOS XR show command output exhibit,
RP/0/RSP1/CPU0:ASR9006#sh mpls ldp igp sync
Bundle-Ether9000:
Sync status: Ready
Peers:
192.168.1.25:0 (GR)
GigabitEthernet0/1/0/10:
Sync status: Not ready
what are three possible reasons that the GigabitEthernet0/1/0/10 LDP IGP sync status is not ready?
A. The OSPF neighbor on GigabitEthernet0/1/0/10 is not up.
B. LDP is up on GigabitEthernet0/1/0/10, but no label bindings have been received from the peer.
C. GigabitEthernet0/1/0/10 is not configured to run LDP.
D. The LDP neighbor on GigabitEthernet0/1/0/10 is not up.
E. Graceful restart is not configured on the peer.
F. GigabitEthernet0/1/0/10 is a member link of Bundle-Ether9000.
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In which two Cisco IOS XR configuration modes can mpls ldp igp sync be configured?
A. config-isis
B. config-ospf
C. config-ldp
D. config-if
E. config-ospf-ar
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On Cisco routers, which three methods can be used to map traffic into the MPLS traffic engineering tunnel?
A. static routing
B. optimized edge routing
C. autoroute
D. on-demand routing
E. policy-based routing
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Which three statements are correct regarding a Cisco MPLS TE?
A. CBR takes into account link resource and traffic tunnel attributes.
B. A Cisco MPLS TE tunnel maps onto an LSP path.
C. RSVP is used between customer routers.
D. A tunnel that is created with a priority of 0 can pre-empt an existing tunnel with a priority of 7.
E. Packets that are mapped into a Cisco MPLS TE tunnel will have two labels, with the top label indicating what the tail-end router should do with the packet.
F. Tunnels are bidirectional by default.
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On a Cisco router, when will the router actually reserve the bandwidth for the MPLS traffic engineering tunnel?
A. on the receipt of the RSVP Resv message
B. during the autoroute process
C. on the receipt of the RSVP Path message
D. during constraint-based routing calculations
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Cisco MPLS TE path setup can be affected by which three tunnel attributes?
A. MTU
B. delay
C. affinity
D. bandwidth
E. priority
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When using the tunnel mpls traffic-eng path-option 1 explicit name test command in Cisco MPLS TE tunnel configurations, the test explicit-path configuration will consist of a list of which values?
A. resource class affinity
B. IP address
C. MPLS label
D. tunnel endpoint
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Cisco MPLS TE resource attributes that are configured locally for each link are distributed to the headend router of the traffic engineering tunnel using which protocol?
A. BGP
B. RSVP
C. LDP
D. OSPF or IS-IS with TE extension
E. MP-BGP
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When implementing Cisco MPLS TE, the constrained-based path calculations will use which value as the TE cost of each link within the MPLS domain?
A. By default, it will use the IGP metric, or each link can be assigned a specific value using the admin-weight command.
B. It can only use the IGP metric as the TE cost.
C. Each link must be assigned a TE cost using the metric command.
D. It will use the interface bandwidth as the TE cost.
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Which affinity and mask value will match the link affinity that has 0x0F in the first 8 bits and 0x01 in the last 8 bits, and the middle 16 bits can be any value?
A. affinity 0x0F000001 mask 0x11111111
B. affinity 0x0F000001 mask 0xFF0000FF
C. affinity 0x0F000001 mask 0x11000011
D. affinity 0x0F000001 mask 0x0F000001
E. affinity 0x0F000001 mask 0x00FFFF00
F. affinity 0x0F000001 mask 0x00000000
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Which two feature are used to provide Cisco MPLS TE node and link protection?
A. fast reroute
B. BFD
C. autoroute
D. backup tunnels
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In Cisco MPLS TE implementations, what can cause the tunnel bandwidth to adjust automatically based on the traffic load in the tunnel?
A. admin weight
B. fast reroute
C. autobandwidth
D. bandwidth subpool
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Which affinity value will be matched by the affinity bit mask of the affinity 0xFF00000A mask 0xFFFF000F command?
A. 0xFF000000
B. 0xFF00EEEA
C. 0x11110001
D. 0x00000000
E. 0xFFFF000A
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Refer to the Cisco IOS XR configuration exhibit.
interface Tunnel-te 10
ipv4 unnumbered Loopback0
destination 10.5.5.5
signalled-bandwidth 1000
priority 7 7
path-option 1 explicit name testpath
!
explicit-path name testpath
index 1 next-address ipv4 unicast 10.3.3.3
index 2 next-address ipv4 unicast 10.4.4.4
!
mpls traffic-eng
interface GigibitEthernet 0/0/0/10
backup-path tunnel-te 10
Which statement is correct?
A. The backup tunnel path is learned dynamically.
B. The fast-reroute command is missing under the (config-mpls-te-if)# configuration mode.
C. Interface gi0/0/0/10 is the protected link.
D. The backup tunnel-te 10 tunnel is using the highest setup and hold priority settings of 7.
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When defining an explicit MPLS TE tunnel path, which two command options are available under the explicit-path configuration mode?
A. include-address
B. dynamic-address
C. next-address
D. exclude-address
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Which three mechanisms are used to implement MPLS TE?
A. LDP
B. CSPF
C. tunnel interface
D. RSVP
E. MP-BGP
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Only based on the Cisco IOS XR policy-map configuration exhibit,
policy-map policy_A
class test
bandwidth 1000000
random-detect dscp AF11 10000 20000
random-detect dscp AF41 12000 24000
which statement is correct?
A. DSCP AF11 and AF41 marked packets are guaranteed a mazimum bandwidth of 1 Mb/s.
B. DSCP AF11 and AF41 marked packets are guaranteed a minimum bandwidth of 1 Mb/s.
C. DSCP AF11 marked packets will be randomly dropped when the average queue length reaches 10,000 packets.
D. All DSCP AF41 marked packets will be dropped when the average queue length reaches 12,000 packets.
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