Sample questions
Cisco SPCOR / CCNP Service Provider Core 350-501 practice questions
Which THREE components are required to deploy MPLS Layer 3 VPN?
Trap 1: GRE tunneling
GRE tunneling is not required; MPLS encapsulation is used.
Trap 2: OSPF
Any IGP (OSPF, IS-IS) can be used; not specifically required.
- A
VRFs on PE routers
VRFs provide per-customer routing separation.
- B
GRE tunneling
Why wrong: GRE tunneling is not required; MPLS encapsulation is used.
- C
OSPF
Why wrong: Any IGP (OSPF, IS-IS) can be used; not specifically required.
- D
LDP
LDP distributes labels for MPLS forwarding.
- E
MP-BGP with VPNv4 address family
MP-BGP carries VPN routes between PEs.
A service provider is designing a new MPLS L3VPN service. The customer requires that their VPN traffic be isolated from other customers and that the provider edge routers maintain separate routing tables for each VPN. Which architectural component is essential for this separation?
Trap 1: MPLS label stacking
Label stacking is used for tunneling and traffic engineering, not for per-VPN routing tables.
Trap 2: VLAN tagging on the customer-facing interfaces
VLAN provides Layer 2 separation but not separate routing tables.
Trap 3: BGP route reflectors
Route reflectors help scale BGP but do not provide per-VPN routing tables.
- A
MPLS label stacking
Why wrong: Label stacking is used for tunneling and traffic engineering, not for per-VPN routing tables.
- B
VRF (Virtual Routing and Forwarding)
VRF creates separate routing tables per VPN instance, enabling isolation.
- C
VLAN tagging on the customer-facing interfaces
Why wrong: VLAN provides Layer 2 separation but not separate routing tables.
- D
BGP route reflectors
Why wrong: Route reflectors help scale BGP but do not provide per-VPN routing tables.
A service provider's network is experiencing suboptimal routing for BGP prefixes received from a customer. The customer is multihomed to two different PE routers in the same AS. Which BGP feature can ensure that traffic ingresses via the correct PE?
Trap 1: Local Preference
Local Preference is used for outbound path selection within an AS.
Trap 2: AS-path prepend
AS-path prepend makes a path less preferred for outbound selection.
Trap 3: Weight
Weight is a Cisco proprietary attribute that affects path selection for routes from the same router.
- A
MED
MED is used to influence inbound traffic by advertising different metrics to different peers.
- B
Local Preference
Why wrong: Local Preference is used for outbound path selection within an AS.
- C
AS-path prepend
Why wrong: AS-path prepend makes a path less preferred for outbound selection.
- D
Weight
Why wrong: Weight is a Cisco proprietary attribute that affects path selection for routes from the same router.
A network engineer is troubleshooting OSPFv3 on a service provider's IPv6 network. The router shows that OSPFv3 adjacency never reaches FULL, says 'Init'. The neighbor is directly connected over a point-to-point link. What is the most likely cause?
Trap 1: LSA throttling prevents exchanges
LSA throttling controls LSA generation, not adjacency formation.
Trap 2: Mismatched OSPF router-id
Mismatched router-id leads to adjacency failure in ExStart state.
Trap 3: Mismatched area IDs
Area ID mismatch causes adjacency to stall in ExStart/Exchange.
- A
LSA throttling prevents exchanges
Why wrong: LSA throttling controls LSA generation, not adjacency formation.
- B
Mismatched OSPF router-id
Why wrong: Mismatched router-id leads to adjacency failure in ExStart state.
- C
Mismatched area IDs
Why wrong: Area ID mismatch causes adjacency to stall in ExStart/Exchange.
- D
Missing 'ipv6 ospf' interface command on one side
OSPFv3 requires explicit interface configuration to activate adjacency.
Which TWO of the following are characteristics of MPLS LDP?
Trap 1: Distributes labels for BGP routes
LDP does not distribute labels for BGP routes unless specifically configured.
Trap 2: Requires an IGP like OSPF for session reachability
LDP session can be established over any reachable IP, not solely IGP.
Trap 3: TCP for both discovery and session
LDP uses UDP for discovery.
- A
Distributes labels for BGP routes
Why wrong: LDP does not distribute labels for BGP routes unless specifically configured.
- B
Label distribution based on IP routing table
By default, LDP distributes labels for all IGP routes.
- C
Requires an IGP like OSPF for session reachability
Why wrong: LDP session can be established over any reachable IP, not solely IGP.
- D
UDP for discovery, TCP for session
LDP uses UDP hellos and TCP for session establishment.
- E
TCP for both discovery and session
Why wrong: LDP uses UDP for discovery.
A customer reports intermittent packet loss on a MPLS L3VPN connection. The PE router shows 'show mpls forwarding' entries for the CE prefix, but ping from the PE to the CE fails intermittently. Which action should be taken to isolate the issue?
Trap 1: Use 'show mpls lsp' to verify the LSP to the CE's PE.
LSP status is for the MPLS path, but the issue may be VRF-related.
Trap 2: Examine the 'show mpls forwarding vrf CUSTOMER' output to see label…
This shows label operations but does not isolate VRF route import issues.
Trap 3: Review the 'show bgp vpnv4 unicast all' output to verify route…
The issue is with MPLS forwarding, not BGP advertisement.
- A
Check 'show ip route vrf CUSTOMER' and 'show bgp vpnv4 unicast vrf CUSTOMER' to confirm the VRF routes.
This verifies that the VRF has the correct routes and that BGP VPNv4 routes are properly imported.
- B
Use 'show mpls lsp' to verify the LSP to the CE's PE.
Why wrong: LSP status is for the MPLS path, but the issue may be VRF-related.
- C
Examine the 'show mpls forwarding vrf CUSTOMER' output to see label operations.
Why wrong: This shows label operations but does not isolate VRF route import issues.
- D
Review the 'show bgp vpnv4 unicast all' output to verify route advertisement.
Why wrong: The issue is with MPLS forwarding, not BGP advertisement.
Refer to the exhibit. An engineer is troubleshooting an MPLS LDP session between two routers. The output shows that the LDP session is operational. However, MPLS labels are not being exchanged. What is the most likely cause?
Exhibit
Router# show mpls ldp neighbor
Peer LDP Ident: 10.1.1.2:0; Local LDP Ident: 10.1.1.1:0
TCP connection: 10.1.1.2.646 - 10.1.1.1.52300
State: Oper; Msgs sent/rcvd: 100/101; Downstream on demand
Up time: 01:23:45
LDP discovery sources:
GigabitEthernet0/0/0; xc: 10.1.1.2:0
Addresses bound to peer LDP Ident:
10.2.2.2 10.3.3.3Trap 1: The peer's addresses are not bound to the LDP Ident.
Addresses are bound as shown.
Trap 2: The TCP connection is not using port 646.
The output shows port 646 is used.
Trap 3: The LDP session is not established.
The session state is Oper, meaning operational.
- A
The peer's addresses are not bound to the LDP Ident.
Why wrong: Addresses are bound as shown.
- B
The TCP connection is not using port 646.
Why wrong: The output shows port 646 is used.
- C
The LDP label advertisement mode is 'downstream on demand'.
In this mode, labels are only sent on request; if the peer expects unsolicited, labels may not be exchanged.
- D
The LDP session is not established.
Why wrong: The session state is Oper, meaning operational.
During an MPLS network migration from LDP to Segment Routing, an engineer notices that some routers are not advertising Prefix-SIDs for certain loopbacks. The IGP is OSPF. What configuration is required on these routers to advertise Prefix-SIDs?
Trap 1: Enable 'mpls ldp autoconfig' on the loopback interface.
This is for LDP, not SR.
Trap 2: Enable 'segment-routing mpls' globally and configure 'prefix-sid…
The prefix-sid is configured under the OSPF router process, not the interface.
Trap 3: Configure 'segment-routing mpls set-adjacency-sid' on the loopback.
Adjacency-SIDs are for interfaces, not loopbacks.
- A
Enable 'mpls ldp autoconfig' on the loopback interface.
Why wrong: This is for LDP, not SR.
- B
Enable 'segment-routing mpls' globally and configure 'prefix-sid index' under the loopback interface.
Why wrong: The prefix-sid is configured under the OSPF router process, not the interface.
- C
Configure 'segment-routing mpls set-adjacency-sid' on the loopback.
Why wrong: Adjacency-SIDs are for interfaces, not loopbacks.
- D
Configure 'segment-routing mpls' globally and assign a SID index under the OSPF router process for the loopback.
This enables SR globally and assigns the Prefix-SID under OSPF.
Which TWO statements about MPLS label switching are correct? (Choose two.)
Trap 1: The CE receives a frame with an MPLS label.
CE receives an IP packet without label (unless configured for MPLS).
Trap 2: PHP (Penultimate Hop Popping) causes the egress router to pop the…
PHP causes the penultimate hop to pop the label, not the egress.
Trap 3: The egress LSR performs label swapping before forwarding.
Egress pops the label, not swap.
- A
The transit LSR performs label swapping.
Correct: Transit routers swap the incoming label with an outgoing label.
- B
The CE receives a frame with an MPLS label.
Why wrong: CE receives an IP packet without label (unless configured for MPLS).
- C
The ingress LSR imposes a label on the packet.
Correct: Ingress does label imposition (push).
- D
PHP (Penultimate Hop Popping) causes the egress router to pop the label.
Why wrong: PHP causes the penultimate hop to pop the label, not the egress.
- E
The egress LSR performs label swapping before forwarding.
Why wrong: Egress pops the label, not swap.
Which THREE of the following are benefits of using Segment Routing over LDP in an MPLS network? (Choose three.)
Trap 1: Provides inherent security against label spoofing.
SR does not add security features.
Trap 2: Requires BGP-LU for label distribution.
SR uses IGP for label distribution; BGP-LU is optional.
- A
Enables traffic engineering without RSVP-TE.
Correct: SR-TE provides traffic engineering capabilities.
- B
Reduces the number of protocols required in the network.
Correct: Fewer protocols to configure and troubleshoot.
- C
Eliminates the need for LDP and RSVP-TE in the core.
Correct: SR uses IGP extensions instead of LDP and RSVP-TE.
- D
Provides inherent security against label spoofing.
Why wrong: SR does not add security features.
- E
Requires BGP-LU for label distribution.
Why wrong: SR uses IGP for label distribution; BGP-LU is optional.
A service provider is deploying MPLS L3VPN and notices that BGP next-hop resolution for VPNv4 routes fails on the PE routers. The PE routers are running OSPF as the IGP and have loopback interfaces used for LDP and BGP peering. Which configuration change should the engineer implement to ensure that the BGP next-hop is reachable?
Trap 1: Configure 'neighbor x.x.x.x allowas-in 1' under the BGP VRF…
This allows AS path repetition, not next-hop resolution.
Trap 2: Apply the 'neighbor x.x.x.x next-hop-self' command under the BGP…
This command changes the next-hop to the PE but does not address reachability of the original next-hop.
Trap 3: Increase the 'maximum-paths' value under the BGP address-family…
This affects multipath but not reachability.
- A
Configure 'neighbor x.x.x.x update-source loopback0' under the BGP router configuration.
This ensures BGP uses the loopback as the source IP, making the next-hop reachable via IGP.
- B
Configure 'neighbor x.x.x.x allowas-in 1' under the BGP VRF configuration.
Why wrong: This allows AS path repetition, not next-hop resolution.
- C
Apply the 'neighbor x.x.x.x next-hop-self' command under the BGP VRF configuration.
Why wrong: This command changes the next-hop to the PE but does not address reachability of the original next-hop.
- D
Increase the 'maximum-paths' value under the BGP address-family VPNv4.
Why wrong: This affects multipath but not reachability.
Which TWO are benefits of using Segment Routing (SR) over traditional LDP-based MPLS?
Trap 1: Requires only OSPF as the IGP.
SR works with both OSPF and IS-IS.
Trap 2: Reduces label imposition at the ingress PE.
SR may increase label stack depth.
Trap 3: Faster convergence due to BGP PIC.
BGP PIC is not exclusive to SR; SR uses IGP convergence.
- A
Eliminates the need for LDP and RSVP-TE protocols.
SR uses IGP to distribute labels, removing LDP and RSVP-TE.
- B
Requires only OSPF as the IGP.
Why wrong: SR works with both OSPF and IS-IS.
- C
Reduces label imposition at the ingress PE.
Why wrong: SR may increase label stack depth.
- D
Faster convergence due to BGP PIC.
Why wrong: BGP PIC is not exclusive to SR; SR uses IGP convergence.
- E
Supports traffic engineering without RSVP-TE.
SR-TE uses segment lists for explicit paths.
A service provider is configuring VRF-lite between two CE routers connected to the same PE. The CE routers are in different VRFs. Which command allows the PE router to forward traffic between the VRFs?
Trap 1: vrf forward RED
Incorrect. 'vrf forward' is not a valid Cisco IOS command.
Trap 2: route-target export RED:100 import BLUE:100
Incorrect. Route-target is used for MPLS VPN route distribution, not for local inter-VRF routing.
Trap 3: ip route vrf RED 0.0.0.0 0.0.0.0 10.1.1.1 global
Incorrect. The 'global' keyword points to the global routing table, not another VRF.
- A
vrf forward RED
Why wrong: Incorrect. 'vrf forward' is not a valid Cisco IOS command.
- B
route-target export RED:100 import BLUE:100
Why wrong: Incorrect. Route-target is used for MPLS VPN route distribution, not for local inter-VRF routing.
- C
ip route vrf RED 0.0.0.0 0.0.0.0 10.1.1.1 global
Why wrong: Incorrect. The 'global' keyword points to the global routing table, not another VRF.
- D
ip route vrf RED 0.0.0.0 0.0.0.0 vrf BLUE
Correct. This command uses the 'vrf' keyword to route between VRFs.
A service provider is deploying MPLS L3VPN and wants to ensure that routes from a specific customer VRF are only advertised to a specific remote PE. Which mechanism should be used?
Trap 1: Configuring a separate VPNv4 address-family for that PE
Incorrect. VPNv4 address-family is a single address-family per BGP process, not per PE.
Trap 2: Using a unique route-distinguisher per VRF
Incorrect. RD distinguishes routes from different VRFs but does not filter which PE receives them.
Trap 3: Setting the next-hop-self on the PE
Incorrect. Next-hop-self changes the next-hop but does not restrict which PE receives the route.
- A
Applying a route-map to the VRF export statement
Correct. A route-map on export can filter routes before they are advertised to other PEs via VPNv4.
- B
Configuring a separate VPNv4 address-family for that PE
Why wrong: Incorrect. VPNv4 address-family is a single address-family per BGP process, not per PE.
- C
Using a unique route-distinguisher per VRF
Why wrong: Incorrect. RD distinguishes routes from different VRFs but does not filter which PE receives them.
- D
Setting the next-hop-self on the PE
Why wrong: Incorrect. Next-hop-self changes the next-hop but does not restrict which PE receives the route.
A service provider is migrating from LDP to Segment Routing. What is the correct order of operations to ensure uninterrupted MPLS forwarding?
Trap 1: Enable SR on all routers simultaneously.
Incorrect. This can cause signaling mismatches and loss of connectivity.
Trap 2: Configure IS-IS SR extensions on all routers, then disable LDP.
Incorrect. Disabling LDP before SR is fully deployed will break MPLS forwarding.
Trap 3: Disable LDP first to free labels, then enable SR.
Incorrect. Disabling LDP first will remove all LDP labels, causing a forwarding outage.
- A
Enable SR on each router one by one while LDP remains active, then remove LDP after SR is stable.
Correct. This gradual migration ensures continuous forwarding via LDP while SR is established.
- B
Enable SR on all routers simultaneously.
Why wrong: Incorrect. This can cause signaling mismatches and loss of connectivity.
- C
Configure IS-IS SR extensions on all routers, then disable LDP.
Why wrong: Incorrect. Disabling LDP before SR is fully deployed will break MPLS forwarding.
- D
Disable LDP first to free labels, then enable SR.
Why wrong: Incorrect. Disabling LDP first will remove all LDP labels, causing a forwarding outage.
In EVPN multihoming with all-active mode, what is the purpose of the aliasing capability?
Trap 1: It permits the use of a single ESI label across all PEs in the ES.
Incorrect. ESI labels are used for split-horizon and are per PE, not shared.
Trap 2: It reduces the number of BGP updates by aggregating MAC routes.
Incorrect. Aliasing may actually increase updates because each PE advertises additional MAC routes.
Trap 3: It allows load balancing of traffic across all PEs.
Incorrect. Load balancing is a result of aliasing, but the specific purpose is to advertise MACs on behalf of other PEs.
- A
It permits the use of a single ESI label across all PEs in the ES.
Why wrong: Incorrect. ESI labels are used for split-horizon and are per PE, not shared.
- B
It reduces the number of BGP updates by aggregating MAC routes.
Why wrong: Incorrect. Aliasing may actually increase updates because each PE advertises additional MAC routes.
- C
It allows load balancing of traffic across all PEs.
Why wrong: Incorrect. Load balancing is a result of aliasing, but the specific purpose is to advertise MACs on behalf of other PEs.
- D
It enables one PE to advertise MAC addresses for another PE in the same ES.
Correct. Aliasing allows a PE to advertise MACs for other PEs in the same ES, making all active paths known.
Refer to the exhibit. A service provider is receiving BGP prefixes from a customer (AS 64512). The provider wants to tag all routes from that customer that match prefix 10.1.0.0/16 or more specific with community 65000:100, while not modifying other routes. After applying the configuration, which statement is true?
Exhibit
router bgp 65000 neighbor 192.168.1.1 remote-as 64512 address-family ipv4 unicast neighbor 192.168.1.1 route-map SET_COMMUNITY in ! route-map SET_COMMUNITY permit 10 match ip address prefix-list MATCH_CUST_A set community 65000:100 additive ! route-map SET_COMMUNITY deny 20 ! ip prefix-list MATCH_CUST_A seq 5 permit 10.1.0.0/16 le 24
Trap 1: Routes with a mask longer than /24 will be rejected by the…
The le 24 allows masks up to /24, not longer.
Trap 2: All routes from the customer will have their communities replaced…
The additive keyword appends, not replaces.
Trap 3: Routes not matching the prefix-list will be denied and not…
Deny in route-map does not filter routes; it only skips setting community.
- A
Only routes matching 10.1.0.0/16 or more specific will have the community added; other routes remain unchanged.
The route-map permits matching routes with additive community, denies others without affecting acceptance.
- B
Routes with a mask longer than /24 will be rejected by the prefix-list.
Why wrong: The le 24 allows masks up to /24, not longer.
- C
All routes from the customer will have their communities replaced with 65000:100.
Why wrong: The additive keyword appends, not replaces.
- D
Routes not matching the prefix-list will be denied and not installed.
Why wrong: Deny in route-map does not filter routes; it only skips setting community.
A service provider is designing a multicast solution for a Layer 3 VPN. They want to use MVPN with BGP signaling (draft-rosen). The PE routers are configured with VRF and multicast routing enabled. Which BGP address family must be enabled between PE routers to carry multicast routing information?
Trap 1: MVPN does not use BGP; it uses PIM.
draft-rosen uses BGP for auto-discovery and signaling.
Trap 2: VPNv4 address family
VPNv4 carries unicast routes only.
Trap 3: IPv4 multicast address family
Global multicast BGP is not for VPN context.
- A
MCAST-VPN address family
The MCAST-VPN address family is used for MVPN signaling.
- B
MVPN does not use BGP; it uses PIM.
Why wrong: draft-rosen uses BGP for auto-discovery and signaling.
- C
VPNv4 address family
Why wrong: VPNv4 carries unicast routes only.
- D
IPv4 multicast address family
Why wrong: Global multicast BGP is not for VPN context.
Which THREE characteristics apply to the BGP-LS (BGP Link State) protocol?
Trap 1: It supports only IS-IS, not OSPF.
Both OSPF and IS-IS are supported.
Trap 2: It carries traffic-engineering parameters in the NLRI.
TE parameters are carried in the BGP-LS attribute, not NLRI.
- A
It supports only IS-IS, not OSPF.
Why wrong: Both OSPF and IS-IS are supported.
- B
It uses a separate address family from VPNv4.
BGP-LS uses AFI 16388, SAFI 71.
- C
It distributes link-state information from IGPs like OSPF and IS-IS.
BGP-LS collects topology from IGPs.
- D
It uses BGP as the transport protocol.
BGP-LS is an address family within BGP.
- E
It carries traffic-engineering parameters in the NLRI.
Why wrong: TE parameters are carried in the BGP-LS attribute, not NLRI.
Refer to the exhibit. A service provider is applying this QoS policy on a PE-CE interface. The business customer complains that voice traffic (marked with DSCP EF) experiences drops during congestion. What is the likely cause?
Exhibit
interface GigabitEthernet0/0/0/0 ipv4 address 10.1.1.1 255.255.255.252 service-policy output QOS_POLICY ! class-map match-any REALTIME match precedence 5 match dscp ef ! policy-map QOS_POLICY class REALTIME priority level 1 police rate percent 10 class class-default bandwidth remaining ratio 1
Trap 1: The priority level is set too low; voice should be priority level 4.
Priority level only affects the order of multiple priority queues; level 1 is highest.
Trap 2: The 'bandwidth remaining ratio' command under class-default is…
The priority queue is not affected by bandwidth remaining ratio.
Trap 3: The policy is applied in the output direction; it should be input.
Output direction is correct for shaping/policing egress traffic.
- A
The police rate under the REALTIME class is limiting voice traffic to 10% of bandwidth.
Policing drops traffic exceeding 10%.
- B
The priority level is set too low; voice should be priority level 4.
Why wrong: Priority level only affects the order of multiple priority queues; level 1 is highest.
- C
The 'bandwidth remaining ratio' command under class-default is starving the priority queue.
Why wrong: The priority queue is not affected by bandwidth remaining ratio.
- D
The policy is applied in the output direction; it should be input.
Why wrong: Output direction is correct for shaping/policing egress traffic.
A network engineer is automating BGP configuration using the Cisco IOS-XE YANG model. They want to enable the 'always-compare-med' feature under BGP. Which XPath expression correctly targets this leaf?
Trap 1: /bgp/global/always-compare-med
Missing the 'native/router' prefix.
Trap 2: /native/router/bgp/always-compare-med
Missing the 'scope/global' containers.
Trap 3: /router/bgp/global/always-compare-med
Missing 'native' container.
- A
/bgp/global/always-compare-med
Why wrong: Missing the 'native/router' prefix.
- B
/native/router/bgp/scope/global/always-compare-med
Correct path according to Cisco IOS-XE YANG model.
- C
/native/router/bgp/always-compare-med
Why wrong: Missing the 'scope/global' containers.
- D
/router/bgp/global/always-compare-med
Why wrong: Missing 'native' container.
A service provider is troubleshooting BGP route advertisement for a VPNv4 prefix. The PE router receives the prefix from the route reflector but does not install it in the VRF routing table. The BGP table shows the prefix as valid but not best. What is the most likely cause?
Trap 1: The VRF does not have the correct route-target import.
If route-target import were missing, the route would not be valid in BGP.
Trap 2: The BGP table is full and cannot accept more prefixes.
The route is already in the BGP table.
Trap 3: The MPLS label is missing in the BGP update.
The route is valid, so label is present.
- A
The VRF does not have the correct route-target import.
Why wrong: If route-target import were missing, the route would not be valid in BGP.
- B
The next-hop is not reachable via the IGP with an MPLS label.
Next-hop unreachability causes the route to be not best.
- C
The BGP table is full and cannot accept more prefixes.
Why wrong: The route is already in the BGP table.
- D
The MPLS label is missing in the BGP update.
Why wrong: The route is valid, so label is present.
Based on the exhibit, which statement is true about the QoS policy?
Exhibit
Refer to the exhibit. class-map match-any VIDEO match ip dscp af41 af42 af43 ! class-map match-all VOICE match ip dscp ef ! policy-map QOS-POLICY class VOICE priority percent 10 class VIDEO bandwidth remaining percent 30 class class-default fair-queue ! interface GigabitEthernet0/0 service-policy output QOS-POLICY
Trap 1: The class-default will use weighted fair queuing (WFQ).
'fair-queue' is used, which is a flow-based queuing, not CBWFQ.
Trap 2: The VIDEO class will be limited to 30% of the total interface…
'bandwidth remaining percent' provides a minimum guarantee, not a maximum limit.
Trap 3: The VIDEO class is guaranteed at least 30% of the total interface…
'bandwidth remaining percent' guarantees a percentage of the remaining bandwidth after priority, not total bandwidth.
- A
The class-default will use weighted fair queuing (WFQ).
Why wrong: 'fair-queue' is used, which is a flow-based queuing, not CBWFQ.
- B
The VIDEO class will be limited to 30% of the total interface bandwidth.
Why wrong: 'bandwidth remaining percent' provides a minimum guarantee, not a maximum limit.
- C
The VOICE class is allocated a strict priority queue with a bandwidth limit of 10% of the interface bandwidth.
The 'priority percent 10' command provides a strict priority queue with a bandwidth limit of 10%.
- D
The VIDEO class is guaranteed at least 30% of the total interface bandwidth.
Why wrong: 'bandwidth remaining percent' guarantees a percentage of the remaining bandwidth after priority, not total bandwidth.
A service provider is implementing QoS on an MPLS network to support voice, video, and data traffic. Which queuing mechanism provides the lowest latency for real-time traffic?
Trap 1: FIFO
FIFO provides no traffic differentiation, leading to unpredictable latency.
Trap 2: WRED
WRED is a congestion avoidance mechanism that drops packets probabilistically, not a queuing mechanism.
Trap 3: CBWFQ
CBWFQ uses class-based weighted fair queuing but does not provide a strict priority queue for real-time traffic.
- A
FIFO
Why wrong: FIFO provides no traffic differentiation, leading to unpredictable latency.
- B
WRED
Why wrong: WRED is a congestion avoidance mechanism that drops packets probabilistically, not a queuing mechanism.
- C
LLQ
LLQ provides a strict priority queue that ensures low latency and jitter for real-time traffic.
- D
CBWFQ
Why wrong: CBWFQ uses class-based weighted fair queuing but does not provide a strict priority queue for real-time traffic.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.