300-420: Designing Cisco Enterprise Networks (ENSLD)

Question #: 1
Topic #: 1
Which two BGP features will result in successful route exchanges between eBGP neighbors sharing the same AS number? (Choose two.)

A. advertise-best-external
B. bestpath as-path ignore
C. client-to-client reflection
D. as-override
E. allow-as-in

Selected Answer: DE

Question #: 2
Topic #: 1
A customer with an IPv4 only network topology wants to enable IPv6 connectivity while preserving the IPv4 topology services. The customer plans to migrate IPv4 services to the IPv6 topology, then decommission the IPv4 topology. Which topology supports these requirements?

A. dual stack
B. 6VPE
C. 6to4
D. NAT64

Selected Answer: A

Question #: 3
Topic #: 1
DRAG DROP –
An engineer is designing an addressing plan for a small business using a single /24 network. Each department must have its own subnet. Drag and drop the subnets from the left onto the requirements of the department they fulfill on the right. Not all options are used.
Select and Place:

Suggestion Answer:

Question #: 4
Topic #: 1
A company is running BGP on a single router, which has two connections to the same ISP. Which BGP feature ensures traffic is load balanced across the two links to the ISP?

A. Multihop
B. Multipath Load Sharing
C. Next-Hop Address Tracking
D. AS-Path Prepending

Selected Answer: B

Question #: 5
Topic #: 1
Company A recently acquired another company. Users of the newly acquired company must be able to access a server that exists on Company A’s network, both companies use overlapping IP address ranges. Which action conserves IP address space and provides access to the server?

A. Use a single IP address to create overload NAT
B. Use a single IP address to create a static NAT entry
C. Build one-to-one NAT translation for every user that needs access
D. Re-IP overlapping address space in the acquired company

Selected Answer: A

Question #: 6
Topic #: 1
Which design consideration should be observed when EIGRP is configured on Data Center switches?

A. Perform manual summarization on all Layer 3 interfaces to minimize the size of the routing table.
B. Prevent unnecessary EIGRP neighborships from forming across switch virtual interfaces.
C. Lower EIGRP hello and hold timers to their minimum settings to ensure rapid route reconvergence.
D. Configure multiple EIGRP autonomous systems to segment Data Center services and applications.

Selected Answer: A

Question #: 7
Topic #: 1
Which design consideration must be made when using IPv6 overlay tunnels?

A. Overlay tunnels that connect isolated IPv6 networks are considered a final IPv6 network architecture.
B. Overlay tunnels should only be considered as a transition technique toward a permanent solution.
C. Overlay tunnels should be configured only between border devices and require only the IPv6 protocol stack.
D. Overlay tunneling encapsulates IPv4 packets in IPv6 packets for delivery across an IPv6 infrastructure.

Selected Answer: B

Question #: 8
Topic #: 1
When a network is designed using IS-IS, which two circuit types are supported? (Choose two.)

A. nonbroadcast multiaccess
B. multiaccess
C. point-to-multipoint
D. nonbroadcast
E. point-to-point

Selected Answer: D

Question #: 9
Topic #: 1
A network solution is being designed for a company that connects to multiple Internet service providers. Which Cisco proprietary BGP path attribute will influence outbound traffic flow?

A. Local Preference
B. MED
C. Weight
D. AS Path
E. Community

Selected Answer: A

Question #: 10
Topic #: 1
Refer to the exhibit. EIGRP has been configured on all links. The spoke nodes have been configured as EIGRP stubs, and the WAN links to R3 have higher bandwidth and lower delay than the WAN links to R4. When a link failure occurs at the R1-R2 link, what happens to traffic on R1 that is destined for a subnet attached to R2?

A. R1 has no route to R2 and drops the traffic
B. R1 load-balances across the paths through R3 and R4 to reach R2
C. R1 forwards the traffic to R3, but R3 drops the traffic
D. R1 forwards the traffic to R3 in order to reach R2

Selected Answer: A

Question #: 11
Topic #: 1
A company is using OSPF between its HQ location and a branch office. HQ is assigned area 0 and the branch office is assigned area 1. The company purchases a second branch office, but due to circuit delays to HQ, it decides to connect the new branch office to the existing branch office as a temporary measure. The new branch office is assigned to area 2. Which OSPF configuration enables all three locations to exchange routes?

A. The existing branch office must be configured as a stub area
B. A virtual link must be configured between the new branch office and HQ
C. A sham link must be configured between the new branch office and HQ
D. The new branch office must be configured as a stub area

Selected Answer: C

Question #: 12
Topic #: 1
Which method will filter routes between EIGRP neighbors within the same autonomous system?

A. distribute-list
B. policy-based routing
C. leak-map
D. route tagging

Selected Answer: A

Question #: 13
Topic #: 1
What are two valid scaling techniques when an EIGRP network is designed that consists of more than 1000 routers? (Choose two.)

A. Use structured hierarchical topology with route summarization
B. Used sub-second timers
C. Use the distribute-list command to filter routes
D. Modify delay parameters on the links
E. Implement multiple EIGRP autonomous systems

Selected Answer: AE

Question #: 14
Topic #: 1
Refer to the exhibit. Which solution decreases the EIGRP convergence time?

A. Enable subsecond timers
B. Increase the hold time value
C. Increase the dead timer value
D. Enable stub routing on the spokes

Selected Answer: D

Question #: 15
Topic #: 1
A router running ISIS is showing high CPU and bandwidth utilization. An engineer discovers that the router is configured as L1/L2 and has L1 and L2 neighbors.
Which step optimizes the design to address the issue?

A. Make this router a DIS for each of the interfaces
B. Disable the default behavior of advertising the default route on the L1/L2 router
C. Configure the router to be either L1 or L2
D. Configure each interface as either L1 or L2 circuit type

Selected Answer: D

Question #: 16
Topic #: 1
Which two routing protocols allow for unequal cost load balancing? (Choose two.)

A. EIGRP
B. IS-IS
C. BGP
D. OSPF
E. RIPng

Selected Answer: AC

Question #: 17
Topic #: 1
Which two steps can be taken to improve convergence in an OSPF network? (Choose two.)

A. Use Bidirectional Forwarding Detection
B. Merge all the areas into one backbone area
C. Tune OSPF parameters
D. Make all non-backbone areas stub areas
E. Span the same IP network across multiple areas.

Selected Answer: AC

Question #: 18
Topic #: 1
Which OSPF area blocks LSA Type 3, 4 and 5, but allows a default summary route?

A. normal
B. stub
C. NSSA
D. totally stubby

Selected Answer: D

Question #: 19
Topic #: 1
Refer to the exhibit. All routers currently reside in OSPF area 0. The network manager recently used R1 and R2 as aggregation routers for remote branch locations and R3 and R4 as aggregation routers for remote office locations. The network has since been suffering from outages, which are causing frequent SPF runs. To enhance stability and introduce areas to the OSPF network with the minimal number of ABRs possible, which two solutions should the network manager recommend? (Choose two.)

A. a new OSPF area for R1 and R2 connections, with R1 and R2 as ABRs
B. a new OSPF area for R3 and R4 connections, with R5 and R6 as ABRs
C. a new OSPF area for R3 and R4 connections, with R3 and R4 as ABRs
D. a new OSPF area for R1, R2, R3, and R4 connections, with R1, R2, R3, and R4 as ABRs
E. a new OSPF area for R1 and R2 connections, with R5 and R6 as ABRs

Selected Answer: BE

Question #: 20
Topic #: 1
An engineer must design a solution to provide backup connectivity between two sites. The engineer plans to use an Internet connection, but company policy requires the connection to be encrypted. Additionally, there are several applications that utilize multicast to deliver video streams between the sites. Which technology should the design include?

A. GRE over IPsec
B. IPsec direct encapsulation
C. GETVPN
D. DMVPN

Selected Answer: A

Question #: 21
Topic #: 1
Refer to the exhibit. An architect must design an IP addressing scheme for a multisite network connected via a WAN transit. The campus site must accommodate
12,000 devices, and the branch sites must accommodate 1,000 devices. Which address scheme optimizes network device resources, contains convergence events to the different blocks of the network, and ensures the network’s future growth?

A. ג€¢ Campus: 10.0.0.0/18 ג€¢ Branch1: 10.0.192.0/21 ג€¢ Branch2: 10.0.200.0/21
B. ג€¢ Campus: 10.0.0.0/16 ג€¢ Branch1: 10.255.0.0/20 ג€¢ Branch2: 10.255.16.0/20
C. ג€¢ Campus: 10.0.0.0/10 ג€¢ Branch1: 10.64.0.0/10 ג€¢ Branch2: 10.128.0.0/10
D. ג€¢ Campus: 10.0.0.0/20 ג€¢ Branch1: 10.0.64.0/21 ג€¢ Branch2: 10.0.128.0/21

Selected Answer: A

Question #: 22
Topic #: 1
Refer to the exhibit. Area 10 is a regular OSPF area, and networks 10.1.1.0/24 and 172.16.1.0/24 are internal. Which design provides optimal routing between both networks when the link between routers C and E fails?

A. Move the link between routers C and D to area 10.
B. Create an OSPF virtual link between routers E and F.
C. Create a tunnel between routers E and F in area 10.
D. Make area 10 a not-so-stubby area.

Selected Answer: A

Question #: 23
Topic #: 1
Refer to the exhibit. An engineer is designing an OSPF network for a client. Requirements dictate that the routers in Area 1 should receive all routes belonging to the network, including EIGRP, except the ones that originated in the RIP domain. Which action should the engineer take?

A. Make area 1 a NSSA.
B. Make area 1 a stub.
C. Make area 1 a standard OSPF area.
D. Make the area 1 routers part of area 0.

Selected Answer: A

Question #: 24
Topic #: 1
An engineer is tasked with designing a dual BGP peering solution with a service provider. The design must meet these conditions:
* The routers will not learn any prefix with a subnet mask greater than /24.
* The routers will determine the routes to include in the routing table based on the length of the mask alone.
* The routers will make this selection regardless of the service provider configuration.
Which solution should the engineer include in the design?

A. Use a route map and access list to block the desired networks, and apply the route map to BGP neighbors inbound.
B. Use a route map and prefix list to block the desired networks, and apply the route map to BGP neighbors outbound.
C. Use an IP prefix list to block the desired networks and apply the IP prefix list to BGP neighbors outbound.
D. Use an IP prefix list to block the desired networks and apply the IP prefix list to BGP neighbors inbound.

Selected Answer: D

Question #: 25
Topic #: 1
An engineer is designing an EIGRP network for a small branch office site where there is only one Layer 3 router. The engineer wants the router to advertise the local LAN network to remote EIGRP neighbors without sending any unnecessary multicast messages on the local LAN. Which action should the engineer take?

A. Use a static default route for this site instead of EIGRP
B. Advertise the local LAN using the network command and the passive-interface feature
C. Redistribute the local LAN network using the redistribute connected command
D. Advertise the local LAN subnet as a stub network

Selected Answer: B

Question #: 26
Topic #: 1
Refer to the exhibit. An architect must design a solution to connect the network behind R3 with the EIGRP network. Which mechanism should be included to avoid routing loops?

A. down bit
B. split-horizon
C. route tags
D. summarization

Selected Answer: C

Question #: 27
Topic #: 1
An architect is creating a migration strategy for a large organization in which the choice made by the application between IPv6 and IPv4 is based on the DNS request. Which migration strategy does the architect choose?

A. AFT for public web presence
B. host-initiated tunnels
C. dual-stack
D. site-to-site IPv6 over IPv4 tunnels

Selected Answer: C

Question #: 28
Topic #: 1
An engineer is creating a design to enable IPv6 to run on an existing IPv4 IS-IS network. The IPv4 and IPv6 topologies will match exactly, and the engineer plans to use the same IS-IS router levels for each protocol per interface. Which IS-IS design is required?

A. multi topology without enabling transition feature
B. multi topology with transition feature enabled
C. single topology without enabling transition feature
D. single topology with transition feature enabled

Selected Answer: C

Question #: 29
Topic #: 1
An engineer must connect a new remote site to an existing OSPF network. The new site consists of two low-end routers, one for WAN, and one for LAN. There is no demand for traffic to pass through this area. Which area type does the engineer choose to provide minimal router resource utilization, while still allowing for full connectivity to the rest of the network?

A. not so stubby
B. totally not so stubby
C. totally stubby area
D. stubby area

Selected Answer: C

Question #: 30
Topic #: 1
Refer to the exhibit. An architect is designing a BGP solution to connect a remote branch to a service provider. There are several prefixes within the branch that the company does not want to be advertised to the Internet. Which solution should the architect use to accomplish this?

A. Attach the No-Export community with the prefixes to exclude.
B. Use the BGP No-Advertise community for the prefixes to exclude.
C. Set the BGP Internet community for all prefixes.
D. Implement the NOPEER community.

Selected Answer: A

Question #: 31
Topic #: 1
Refer to the exhibit. AS65533 and AS65530 are announcing a partial Internet routing table as well as their IP subnets. An architect must create a design that ensures AS64512 does not become a transit AS. Which filtering solution must the architect choose?

A. no-advertise
B. next-hop
C. no-export
D. maximum-prefix

Selected Answer: C

Question #: 32
Topic #: 1
Refer to the exhibit. An architect must create a stable and scalable EIGRP solution for a customer. The design must:
✑ conserve bandwidth, memory, and CPU processing
✑ prevent suboptimal routing
avoid any unnecessary queries

Which two solutions must the architect select? (Choose two.)

A. route summarization
B. prefix lists
C. distribute lists
D. stub routing
E. static redistribution

Selected Answer: AD

Question #: 33
Topic #: 1
Refer to the exhibit. An architect must design a solution to connect the two ASs. To optimize bandwidth, the design will implement load sharing between router R6 and router R1. Which solution should the design include?

A. Use update-source to specify the Loopback interface.
B. Use next-hop-self attributes only for routes that are learned from eBGP peers.
C. Configure the eBGP TTL to support eBGP multihop.
D. Use maximum-paths to install multiple paths in the routing table.

Selected Answer: D

Question #: 34
Topic #: 1
A customer’s environment includes hosts that support IPv6-only. Several of these hosts must communicate with a public web server that has only IPv4 domain name resolution. Which solution should the customer use in this environment?

A. utilize NAT64 to translate the addresses
B. implement NAT44 at the edge of the customer network
C. use 6to4 and a tunnel to translate the addresses
D. implement 6PE to resolve hostname resolution

Selected Answer: A

Question #: 35
Topic #: 1
A company is planning to open two new branches and allocate the 2a01:c30:16:7009::3800/118 IPv6 network for the region. Each branch should have the capacity to accommodate a maximum of 200 hosts. Which two networks should the company use? (Choose two.)

A. 2a01:0c30:0016:7009::3a00/120
B. 2a01:0c30:0016:7009::3b00/121
C. 2a01:0c30:0016:7009::3a80/121
D. 2a01:0c30:0016:7009::3c00/120
E. 2a01:0c30:0016:7009::3b00/120

Selected Answer: D

Question #: 36
Topic #: 1
Refer to the exhibit.

A network engineer must improve the current IS-IS environment. The Catalyst switch is equipped with dual supervisors. Each time a stateful switchover occurs, the network experiences unnecessary route recomputation. Which solution addresses this issue if the upstream router does not understand graceful restart messaging?

A. Enable IS-IS remote LFA FRR on both devices.
B. Enable NSR on the switch.
C. Enable NSF on the switch.
D. Configure ISIS aggressive timers on both devices.

Selected Answer: B

Question #: 37
Topic #: 1
Refer to the exhibit.

An architect must design an IGP solution for an enterprise customer. The design must support:
✑ Physical link flaps should have minimal impact.
✑ Access routers should converge quickly after a link failure.
Which two ISIS solutions should the architect include in the design? (Choose two.)

A. Use BGP to IS-IS redistribution to advertise all Internet routes in the Level 1 area.
B. Advertise the IS-IS interface and loopback IP address toward the Internet and data center.
C. Reduce SPF and PRC intervals to improve convergence time.
D. Configure all access and aggregate routers to establish Level 1 / Level 2 adjacencies across the network.
E. Configure access routers to establish a Level 1 adjacency and aggregate routers to establish a Level 1 / Level 2 adjacency.

Selected Answer: CE

Question #: 38
Topic #: 1
Refer to the exhibit.

An engineer is designing a routing solution for a customer. The design must ensure that a failure of network 10.1.0.0/24, 10.1.2.0/24, 10.2.1.0/24, or 10.2.3.0/24 does not impact the core. It also requires fast convergence time during any link failover in the core or access networks.
Which solution must the engineer select?

A. Add aggregation layer between core and access networks.
B. Enable graceful restart on routers A and C.
C. Enable FRR for the connected networks of routers A and C.
D. Enable summarization on routers A and C.

Selected Answer: D

Question #: 39
Topic #: 1
Refer to the exhibit.

A network engineer is designing a network for AS100. The design should ensure that all traffic enters AS100 via link 1 unless there is a network failure. In the event of a failure, link 2 should function as the path for incoming traffic. Which solution should the design include?

A. Modify the next-hop attribute on R3.
B. Use AS-Path prepending on R3.
C. Modify the next-hop attribute on R4.
D. Use AS-Path prepending on R4.

Selected Answer: B

Question #: 40
Topic #: 1
Refer to the exhibit.

An architect must design a solution that uses the direct link between R1 and R2 for traffic from 10.10.10.0/24 toward network 10.10.20.0/24. Which solution should the architect include in the design?

A. Configure the OSPF cost of the link to a value lower than 30.
B. Lower the Administrative Distance for OSPF area 0.
C. Place the link into area 2 and install a new link between R1 and R2 in area 0.
D. Configure the link to provide multiarea adjacency.

Selected Answer: D

Question #: 41
Topic #: 1
Refer to the exhibit.

An engineer must design a WAN solution so that ISP-1 is always preferred over ISP-2. The path via ISP-2 is considered as a backup and must be used only when the path to ISP-1 is down. Which solution must the engineer choose?

A. R1: – Routes advertised to ISP-1: 0x AS-path prepend – Routes received from ISP-1: HIGH local-preference – Routes advertised to R2: no action – Routes received from R2: community NO-EXPORT R2: – Routes advertised to ISP-2:5x AS-path prepend – Routes received from ISP-2: LOW local-preference – Routes advertised to R1: community NO-ADVERTISE – Routes received from R1: no action
B. R1: – Routes advertised to ISP-1: 0x AS-path prepend – Routes received from ISP-1: HIGH local-preference – Routes advertised to R2: community NO-EXPORT – Routes received from R2: no action R2: – Routes advertised to ISP-2: 5x AS-path prepend – Routes received from ISP-2: LOW local-preference – Routes advertised to R1: no action – Routes received from R1: no action
C. R1: – Routes advertised to ISP-1: 0x AS-path prepend – Routes received from ISP-1: LOW local-preference – Routes advertised to R2: community NO-ADVERTISE – Routes received from R2: no action R2: – Routes advertised to ISP-2: 5x AS-path prepend – Routes received from ISP-2: HIGH local-preference – Routes advertised to R1: no action – Routes received from R1: community NO-ADVERTISE
D. R1: – Routes advertised to ISP-1: 5x AS-path prepend – Routes received from ISP-1: LOW local-preference – Routes advertised to R2: community NO-ADVERTISE – Routes received from R2: no action R2: – Routes advertised to ISP-2: 0x AS-path prepend – Routes received from ISP-2: HIGH local-preference – Routes advertised to R1: community NO-EXPORT – Routes received from R1: no action

Selected Answer: B

Question #: 42
Topic #: 1
Which feature must be incorporated into the campus LAN design to enable Wake on LAN?

A. dynamic ARP Inspection Snooping on layer 2 devices
B. directed broadcasts on layer 3 devices
C. proxy ARP on layer 3 devices
D. DHCP Snooping on layer 2 devices

Selected Answer: B

Question #: 43
Topic #: 1
Refer to the exhibit. An engineer must optimize the traffic flow of the network. Which change provides a more efficient design between the access layer and the distribution layer?

A. Add a link between access switch A and access switch B
B. Reconfigure the distribution switch A to become the HSRP Active
C. Change the link between distribution switch A and distribution switch B to be a routed link
D. Create an EtherChannel link between distribution switch A and distribution switch B

Selected Answer: B

Question #: 44
Topic #: 1
Which first hop redundancy protocol ensures that load balancing occurs over multiple routers using a single virtual IP address and multiple virtual MAC addresses?

A. GLBP
B. IRDP
C. VRRP
D. HSRP

Selected Answer: A

Question #: 45
Topic #: 1
A company with multiple service providers wants to speed up BGP convergence time in the event a failure occurs with their primary link. Which approach achieves this goal and does not impact router CPU utilization?

A. Utilize BFD and tune the multiplier to 50
B. Lower the BGP hello interval
C. Decrease the BGP keepalive timer
D. Utilize BFD and keep the default BGP timers

Selected Answer: D

Question #: 46
Topic #: 1
An engineer is designing an enterprise campus network. The LAN infrastructure consists of switches from multiple vendors, and Spanning Tree must be used as a
Layer 2 loop prevention mechanism. All configured VLANs must be grouped in two STP instances. Which standards-based Spanning Tree technology supports this design solution?

A. MSTP
B. RSTP
C. Rapid PVST
D. STP

Selected Answer: B

Question #: 47
Topic #: 1
A network engineer must segregate three interconnected campus networks using IS-IS routing. A two-layer hierarchy must be used to support large routing domains and to avoid more specific routes from each campus network being advertised to other campus network routers automatically. Which two actions does the engineer take to accomplish this segregation? (Choose two.)

A. Designate two IS-IS routers as BDR routers at the edge of each campus, and configure one BDR for all Level 1 routers and one BDR for all Level 2 routers.
B. Designate two IS-IS routers from each campus to act as Level 1/Level 2 backbone routers at the edge of each campus network.
C. Assign the same IS-IS NET value for each campus, and configure internal campus routers with Level 1/Level 2 routing.
D. Utilize different MTU values for each campus network segment. Level 2 backbone routers must utilize a larger MTU size of 9216.
E. Assign a unique IS-IS NET value for each campus, and configure internal campus routers with Level 1 routing.

Selected Answer: C

Question #: 48
Topic #: 1
Which consideration must be taken into account when using the DHCP relay feature in a Cisco SD-Access Architecture?

A. DHCP-relay must be enabled on fabric edge nodes to provide the correct mapping of DHCP scope to the local anycast gateway.
B. A DHCP server must be enabled on the border nodes to allow subnets to span multiple fabric edges.
C. DHCP servers must support Cisco SD-Access extensions to correctly assign IPs to endpoints in an SD-Access fabric with anycast gateway.
D. DHCP Option-82 must be enabled to map the circuit IP option to the access fabric node where the DHCP discover originated.

Selected Answer: D

Question #: 49
Topic #: 1
Which function are fabric intermediate nodes responsible for in an SD-Access Architecture?

A. mapping EIDs to RLOCs
B. encapsulating user traffic in a VXLAN header including the SGT
C. registering new endpoints in the HTDB
D. transporting IP packets between edge nodes and border nodes

Selected Answer: D

Question #: 50
Topic #: 1
How do endpoints inside an SD-Access network reach resources outside the fabric?

A. a VRF fusion router is used to map resources in one VN to another VN
B. Fabric borders use VRFs to map VNs to VRFs
C. SD-Access transit links are used to transport encapsulated traffic from one fabric to another
D. A fabric edge is used to de-encapsulate VXLAN traffic to normal IP traffic then transported over the outside network

Selected Answer: D