Advanced Addressing and Routing Solutions (25%)

ENSLD · 75 questions

• A large hospital runs IS-IS as the sole IGP across four areas with frequent maintenance windows and strict change control. Adjacencies must reject spoofed hellos and LSPs must survive brief link flaps without flooding churn. Which IS-IS authentication and stability tuning approach best meets these goals?
• An enterprise OSPF backbone with 800 routers suffers CPU spikes during flapping of edge links, causing repeated full SPF runs and flooding of unstable LSAs. Stability must improve without hiding needed topology changes. Which OSPF scaling design using timers and suppression best stabilizes the network?
• A multihomed enterprise receives full Internet routes from two ISPs and must block private prefixes inbound, limit peer advertisements to its own aggregate, and deny routes with an unwanted transit AS in the path. Which basic BGP route filtering design applies the right tool to each goal?
• A university has four regional hubs each serving dozens of closets, and the core routing table is growing with flapping access prefixes that destabilize the backbone. The goal is clean summarization at each hub and stable core updates. Which hierarchical IPv4 plan should the designer create to enable summarization at distribution boundaries?
• A logistics firm with 30 sites on private IPv4 behind NAT is acquiring two companies, adding IoT sensors, and struggling with overlapping addresses and NAT troubleshooting. It needs scalable growth for five years, simple mergers, and reduced translation complexity. Which addressing strategy best supports long-term growth and operational simplicity?
• A retail chain runs EIGRP across 600 stores with slow WAN links where a single branch flap triggers queries that stall convergence network-wide. The design must limit query range and keep branch routers from transiting traffic. Which EIGRP query scoping approach using stub and summarization best contains this problem?
• A logistics firm must connect new IPv6-only sensors across regional sites, but the core remains IPv4-only with no upgrade window and limited MTU headroom. Routing changes must stay minimal at the core. Which overlay tunneling approach for IPv6 across IPv4 infrastructure best fits this migration?
• A manufacturing site has 60 point-to-point router links, 12 server VLANs needing about 40 hosts each, and a tight /22 enterprise allocation with audit pressure to reduce waste. Growth on links is minimal but servers may double. Which VLSM planning approach should the designer use to avoid address waste on links?
• A manufacturing firm is dual-homed to one ISP with two links and must make all internal routers prefer the primary exit for outbound traffic, while asking the ISP to prefer the primary ingress path without changing the local AS path length. Which BGP path-preference attribute design achieves that outbound and inbound influence?
• A bank is planning native dual-stack on its campus and data center where most switches and firewalls already support IPv6. Operations worries about doubling troubleshooting load, security gaps, and inconsistent feature support. Which native dual-stack design consideration best addresses long-term operability?
• A national bank runs IS-IS across 80 routers with a stable core and many regional branches, needing loop-free hierarchy, summarized branch prefixes, and minimal link-state flooding to branches. Designers must choose router roles and adjacency types that enforce a two-tier boundary. Which IS-IS level design creates a stable and scalable hierarchy?
• A regional utility runs OSPF between substations over private MPLS and a multipoint Ethernet service linking three control centers that keeps electing an unstable DR. Security audit requires authentication of all OSPF exchanges. Which OSPF authentication and network type design should the designer select for stability and security?
• A hotel chain operates IPv4 for legacy property systems, IPv6 for new guest Wi-Fi, and needs to keep staff, guest, and building-automation traffic isolated while extending routes to an MPLS provider. Which BGP address family design should the designer adopt for multiprotocol and VPN isolation?
• A national retailer runs one autonomous system across 30 WAN routers in a single IGP domain. iBGP full-mesh sessions are growing sharply, CPU is spiking during best-path churn, and the team must keep one externally visible ASN with minimal administrative split. Which BGP iBGP scaling design reduces sessions while preserving a single autonomous system?
• A regional retailer runs EIGRP named mode with dual hub links where the backup path has a higher feasible distance and stays idle, wasting capacity during peak sales. Design requires hierarchical address families, preserved metrics, and controlled use of the slower path. Which EIGRP metric design enables unequal-cost load sharing in named mode?
• A regional hospital runs IPv6-only tablets on new wards that must reach an IPv4-only patient records server the vendor will not upgrade, DNS is centrally managed, and dual-stack on the endpoints is prohibited by security policy. Which IPv4/IPv6 translation approach fits these boundary constraints?
• A freight operator runs IS-IS with Level-1 warehouse areas and Level-1-2 core routers connecting to two data centers. Area prefixes are flooding into the backbone unsummarized, narrow metrics cap path costs, and remote sites lack a return route to a shared services summary. Which IS-IS route leaking, summarization and metric style design meets all requirements?
• A university has a global /32 from its RIR, four large campuses, and hundreds of VLANs for classrooms, labs, and housing needing stable addresses plus room for research growth. The design must keep routing summaries clean and preserve standard subnet sizing. Which IPv6 address allocation with prefix hierarchy best meets the structured addressing requirement?
• A regional ISP peers with two upstreams and a customer AS 64500. Requirements are to accept only the customer aggregate, block private AS numbers inbound, and prevent your AS from becoming transit between upstreams. Which BGP route-filtering approach enforces prefix scope, AS-path sanity, and transit protection together?
• A bank expands EIGRP to remote branches over unstable links and sees stuck-in-active events, rogue route injection risk, and branch routers transiting core traffic. Security mandates neighbor authentication using per-interface credentials rather than one shared secret for the whole network. Which EIGRP authentication and stability design hardens and stabilizes the deployment?
• A logistics company runs a multi-area IS-IS backbone, sees neighbor flaps after congestion, faces spoofed hello risk on a metro link, and needs faster failure detection without creating instability. Which IS-IS authentication and stability tuning design provides secure and stable adjacencies?
• A multihomed enterprise has two equally capable eBGP transit links and needs both links active for the same prefixes, plus consideration of unequal provider capacities on future links. Which BGP load-sharing design provides active-active use with support for weighted distribution?
• A retailer with 300 stores uses overlapping 10.0.0.0/8 private IPv4, complex NAT at every merger, and is exhausting addresses for IoT sensors and cameras with cloud migration planned. Growth requires simpler routing and end-to-end reachability. Which addressing strategy using private IPv4, NAT, and IPv6 best supports scalable growth?
• A logistics company has four regions with 25 branches each, each branch needs three subnets, the WAN must stay stable as sites are added, and the design must minimize routing table size. Which hierarchical IPv4 addressing method enables clean route summarization at distribution boundaries?
• A retail enterprise has OSPF Area 0 at headquarters, 80 small stores with only a default route need, and one acquisition site redistributing external routes that must reach headquarters without leaking everywhere. Which OSPF multi-area design contains LSAs while preserving required external reachability?
• A logistics firm must connect isolated IPv6 sensor islands across a large IPv4-only core that cannot be upgraded this year, with deterministic endpoints managed by the network team. Which overlay tunneling approach carries IPv6 across the IPv4 infrastructure in this environment?
• An enterprise has two edge routers to different providers, needing all outbound Internet traffic to exit via Router-A, return traffic for its public prefix to enter via Router-A, with Router-B strictly backup. Which BGP attribute design should the designer apply for coordinated path preference?
• A large campus EIGRP network suffers SIA events and slow convergence because every remote site receives queries for every lost route, has many low-speed spoke routers, and needs to preserve optimal summarization at distribution. Which EIGRP query scoping design with stub routers and summarization best limits the impact?
• An enterprise has a central data-center core and six regional campuses that must limit link-state flooding, keep campus failures from destabilizing the core, and allow controlled route leaking for shared services. Which IS-IS level 1 versus level 2 design best creates a stable hierarchy?
• A school district must address 40 new point-to-point WAN links and 10 server farm subnets expecting up to 50 hosts each, public space is limited, and future growth must be supported without renumbering. Which VLSM planning choice avoids waste while preserving usability?
• A national retailer runs a single AS with 60 iBGP routers across four regions and full-mesh peering is becoming unmanageable. Leadership requires keeping one AS number, centralizing routing policy, and minimizing reconfiguration on every router. Which iBGP scaling approach should the designer select to meet these scaling goals?
• A regional hospital is refreshing core, distribution, and access switches and wants IPv6 end-to-end where possible. Printers and an old imaging system remain IPv4-only, and the team wants one operational model plus consistent ACLs and monitoring. Which native dual-stack design best meets the IPv6 migration requirement?
• A regional bank has OSPF Area 0 at headquarters, Area 10/20 at branches with 200 LAN prefixes, and a data-center router redistributing 300 acquired-company routes. Leadership wants smaller branch tables, faster convergence, and contained redistribution faults. Which OSPF summarization placement best meets the requirements?
• A regional bank runs EIGRP named mode with dual MPLS paths where the backup path has higher delay, wants loop-free unequal-cost sharing from feasible successors, and must keep metric calculation consistent. Which EIGRP metric and unequal-cost design achieves this load-sharing goal?
• A multinational enterprise has a registered global prefix, five large campuses, and plans for hundreds of VLANs, point-to-point links, and loopbacks with easy summarization and future growth. The team wants consistent subnetting without address scarcity. Which IPv6 prefix hierarchy with site and subnet sizing should the addressing plan adopt?
• A bank runs IS-IS with Level-1 access areas in each city and a Level-2 backbone, needing to limit Level-1 database size, advertise only a default plus summaries upward, and keep metrics comparable across old and new routers. Which IS-IS route leaking, summarization and metric design should the designer specify to meet scale and compatibility?
• A regional enterprise has two eBGP links from one border router to the same neighbor AS, one 1 Gbps and one 10 Gbps, and wants both links to carry traffic proportionally without manual route tuning. CPU and memory headroom is sufficient for extra paths. Which BGP load-sharing design should the designer select to achieve proportional use of these links?
• A hotel chain now offers IPv6-only guest Wi-Fi to simplify addressing, yet guests still need legacy IPv4-only booking and streaming sites. The design must require no client software and must preserve DNS behavior for address selection. Which IPv4/IPv6 translation at the boundary best fits this scenario?
• A large OSPF campus with 800 routers sees CPU spikes when access-layer links flap, flooding many transit LSAs and triggering repeated full SPF runs. The design must dampen churn while keeping loop-free convergence. Which OSPF scaling tuning with LSA throttling, SPF timers, and prefix suppression fits?
• A logistics IS-IS backbone flaps when warehouse links bounce, unauthenticated adjacencies were spoofed in a lab test, and LSP floods cause CPU spikes. Stability must improve without hiding real failures. Which IS-IS authentication and stability tuning approach should the designer specify for secure steady operation?
• A growing logistics firm has exhausted its 10.0.0.0/8 plan after acquisitions, with overlapping addresses, complex NAT on WAN edges, and new IoT networks demanding thousands of subnets. Leadership wants simpler routing and sustainable growth. Which private IPv4, NAT, and IPv6 strategy should the designer recommend for scalable expansion?
• A manufacturing campus runs EIGRP across 80 sites with flapping remote links causing core queries, needs encrypted neighbor authentication, and must limit query scope from unstable branches. Which EIGRP authentication and stability design best contains this query problem?
• A county government has 12 buildings aggregated by two distribution switches per region, with frequent moves and new subnets straining routing tables. The design must limit updates and simplify growth while preserving resiliency. Which hierarchical IPv4 plan best enables route summarization at distribution and region boundaries?
• A hospital campus redesign uses OSPF over Ethernet with redundant broadcast segments, point-to-point fiber links, and strict HIPAA adjacency spoofing concerns. Convergence must be fast and neighbor formation predictable. Which OSPF authentication and network type choice best fits the design?
• A regional healthcare system runs dual-stack IPv6 in its two data centers but leases an IPv4-only private WAN that the carrier will not upgrade this year. Radiology imaging must flow over IPv6 between the data centers with fixed endpoints, predictable routing, and simple packet captures for compliance audits. Which overlay tunneling approach for IPv6 across IPv4 infrastructure best meets these needs?
• A regional retailer has a hub router in Chicago with 180 EIGRP spokes across slow DSL links. Route flaps at one store cause SIA events and CPU spikes at the hub, and the design must keep spoke routing tables small while allowing spokes to reach headquarters only. Which EIGRP query-scoping design best contains queries and meets summarization needs?
• A regional bank connects a headquarters campus to 25 branches on one flat IS-IS domain today, with dual core routers linking to a data center backbone. Each branch becomes its own area and branches should hide their LAN prefixes from each other and forward inter-branch traffic through the cores. Which IS-IS level design achieves hierarchical scaling for this topology?
• A manufacturer has a backbone Area 0 and a remote plant in Area 10 with one ABR, low-memory routers, and flapping WAN prefixes causing churn. The plant must redistribute one local partner static route while hiding backbone interarea routes and outside externals. Which OSPF area type design gives stable, minimal tables with local redistribution?
• An enterprise runs IPv4 internally, is adding IPv6 for new buildings, and connects to a provider MPLS VPN that carries customer routes as VPNv4. Route policies must stay separate per protocol. Which BGP address-family design best supports this IPv4, IPv6, and VPN requirement?
• A large university runs IPv4 everywhere with modern switches, routers and Windows clients and wants to add IPv6 for research labs without tunneling or translation. The team can upgrade routing, DHCP, DNS and monitoring, but worries about doubling troubleshooting and security workload. Which native dual-stack design addresses its operational considerations?
• A regional retailer received 10.20.16.0/22 and must address 12 WAN point-to-point links plus four stores each needing a 120-host server VLAN while preserving space for growth. Which VLSM allocation prevents address waste on point-to-point and server links for this IPv4 plan?
• An enterprise OSPF domain has Area 5 with 200 branch subnets behind one ABR and a data-center ASBR redistributing 300 external routes. Tables are large and flaps in branches ripple into Area 0. Which OSPF summarization design at ABRs and ASBRs best improves stability and scale?
• A university links its main and research campuses with 10-Gbps fiber and a 2-Gbps microwave backup running EIGRP named mode. The design must use both paths in proportion to capacity, remain loop-free, and keep metrics stable during congestion. Which EIGRP named-mode metric design enables proportional unequal-cost load sharing?
• An enterprise received 2001:db8:1000::/40 from its RIR and must serve eight regional sites with room for growth, each site needing many user and data center subnets. The design standard is a uniform /64 for every VLAN and every router-to-router link. Which IPv6 allocation implements prefix hierarchy with /48 sites and /64 subnets for this enterprise?
• An enterprise IS-IS backbone connects four areas through Level 1-2 routers, with hundreds of branch LANs causing large Level 2 tables and suboptimal paths for shared services. Which IS-IS route leaking, summarization and metric style design stabilizes and optimizes inter-area routing?
• An enterprise dual-homed to two ISPs receives full BGP tables and must accept only its allocated aggregate, block bogons and overly specific prefixes, and drop routes with an unwanted transit AS in the path. Which basic BGP filtering design best enforces this policy requirement?
• A campus has thousands of IPv6-only IoT sensors that must reach an IPv4-only building management platform and public IPv4 DNS names, with no plan to dual-stack the sensors. The team needs automatic address synthesis and name resolution without per-device static mappings. Which translation design at the boundary fits, and which pairing applies?
• A bank backbone runs IS-IS with strict compliance requiring neighbor authentication, plus frequent access-layer flaps that trigger unwanted backbone SPF runs and slow convergence on link failures. Which IS-IS authentication and stability tuning approach secures and stabilizes this backbone?
• A regional bank connects 80 branches over private MPLS with frequent edge flaps and an audit finding of unauthenticated EIGRP updates. The design must verify every neighbor, contain query scope on flaps, and hide branch instability from the core. Which EIGRP stability and authentication design meets all three needs?
• A retail enterprise runs OSPF across 300 stores with a flapping IoT VLAN causing repeated SPF calculations and high CPU, plus hundreds of unneeded transit link addresses bloating the RIB. Convergence must stay fast for real failures while damping instability and hiding infrastructure prefixes. Which OSPF LSA throttling, SPF timer and prefix suppression design meets all requirements?
• A regional hospital group has 180 clinics using 10.0.0.0/16 with overlapping subnets from mergers, heavy NAT at each site, and a five-year plan to add 300 IoT subnets and direct cloud connectivity. Growth is blocked by address conflicts and NAT troubleshooting. Which addressing strategy best supports scalable growth with simplified routing?
• A regional bank is dual-homed to ISP-A as primary and ISP-B as backup with two border routers sharing iBGP. Outbound traffic from all internal sites must prefer ISP-A, while inbound Internet traffic should also prefer ISP-A without affecting internal router decisions. Which BGP path-preference attribute design best meets both requirements?
• A retailer has four regions with 30 stores each and dual distribution switches per region back to a campus core. Growth requires adding stores without renumbering and keeping core tables small. Which hierarchical IPv4 allocation enables clean route summarization at distribution boundaries?
• A national bank runs IS-IS across 120 routers with a core mesh and 25 branch areas that must stay isolated from core churn, hide branch prefixes, and allow controlled expansion without full mesh flooding. The architects need clear hierarchy. Which IS-IS level 1 versus level 2 design creates a stable hierarchy for this network?
• A university network will grow from 8 to 28 iBGP routers in one AS with multiple points of presence, and full-mesh peering is becoming operationally heavy with churn and configuration burden. Designers need stable loop-free scaling without splitting the AS or renumbering. Which iBGP scaling design for route reflectors and confederations best fits this requirement?
• A bank campus expands OSPF across new fiber links that include broadcast Ethernet segments and point-to-point dark fiber, with strict requirements to block spoofed adjacency formation and to reduce DR election delays on stable links. Which OSPF authentication and network type combination secures and stabilizes the design?
• A hospital has a central campus with data center external routes and 40 small clinics with single ABRs, stub routers and no local ASBRs, where clinic routers have limited memory and need minimal LSAs plus a default exit. Which OSPF multi-area design with area types best scales the clinics while preserving data center reachability?
• A retail chain has a single 10.20.0.0/16 block to number 80 point-to-point WAN links and 30 store server VLANs with up to 45 hosts each, and must reserve room for growth without requesting more space. The design must minimize waste on links while keeping server broadcast domains efficient. Which VLSM plan for point-to-point and server links best conserves addresses?
• An enterprise runs IPv4 Internet peering, new IPv6 internal reachability, and MPLS VPNs to isolate finance and engineering across the backbone, needing separate policy and next-hop handling per traffic class. A single BGP session per peer is preferred. Which BGP address family design supports IPv4, IPv6 and VPN isolation?
• An EIGRP WAN has 300 remote spokes behind slow links, with SIA events after core link flaps and excessive queries reaching every branch. Stability requires bounded query domains while keeping branch configs simple. Which EIGRP query-scoping design meets the stability requirement?
• A distribution design uses EIGRP over mixed 10G fiber and 1G backup links, requiring controlled use of the backup without equalizing path costs and simplified config across address families. Which EIGRP named mode design with metrics and load-sharing behavior satisfies the requirement?
• An e-commerce firm has two eBGP exit links from one border router to the same ISP, one 1 Gbps and one 400 Mbps, and needs both links to carry egress traffic roughly proportional to capacity without complex policies. Which BGP load-sharing design best achieves efficient use of unequal links?
• A bank plans IPv6 for 12 large sites with 300 VLANs each, needing aggregation at the WAN core and room for future sites and technologies. Which IPv6 prefix hierarchy with /48 sites and /64 subnets provides scalable allocation?
• A university runs multi-area OSPF with a backbone data center that redistributes Internet routes, while campus ABRs see hundreds of building /24s that churn during maintenance. The design must shrink tables and hide churn without hiding external policy. Which OSPF summarization at ABRs and ASBRs best achieves stable scaling?
• A retail IS-IS network has Level 1 stores, Level 2 core, excessive leaking causing large store tables, inconsistent metrics after migration, and need for 10 aggregate routes at borders. Stability is the goal. Which IS-IS route leaking, summarization and metric style combination best stabilizes this hierarchy?