Question 420
A network router and DX port both support MACsec but traffic fails when the key settings are inconsistent. What is the most suitable design or configuration?
- Align MACsec connectivity association keys and chosen encryption parameters
- Verify current MACsec eligibility and choose an approved dedicated connection when needed
- Add TLS or IPsec where end-to-end encryption is required
- Combine diverse physical connections with supported MACsec or suitable IPsec overlays
Explanation
Correct Answer
A:The approach ensures the Ethernet peers can establish compatible link encryption; BGP route preferences are irrelevant until the encrypted physical link works, directly enabling successful authenticated MACsec operation in this situation.
Incorrect Answers
B:This approach selects a DX connection model that actually supports required physical-link cryptography; hosted connection capabilities are not equivalent to every dedicated-port MACsec option, which helps with supported link-layer encryption deployment instead of delivering successful authenticated MACsec operation.
C:This alternative encrypts traffic at a higher protocol layer beyond the individual Ethernet link; MACsec protects the applicable physical Ethernet hop rather than all subsequent routes, so it addresses application or tunnel confidentiality beyond DX link encryption rather than the required successful authenticated MACsec operation.
D:Although this setting separates circuit redundancy from cryptographic protection, using a single encrypted link still leaves a physical single point of failure; this concerns resilient encrypted hybrid connectivity, not the specified successful authenticated MACsec operation.
Question 421
A maintenance workflow must stop further network mutations if the first account's route update fails. Which AWS networking approach meets this constraint?
- Implement explicit error handling and compensation in the automation workflow
- Use AWS SDK or CLI Describe and List APIs with assumed account roles
- Make the resource automation idempotent with discovery before create operations
- Query the relevant route tables through EC2 or Transit Gateway APIs
Explanation
Correct Answer
A:This configuration prevents incomplete sequences from continuing silently across environments; success messages alone cannot guarantee all dependent resources were updated, so it delivers fail-safe orchestration of network API changes under the stated constraints.
Incorrect Answers
B:The proposed action queries networking resource metadata through authorized API calls; console screenshots are not structured or repeatable inventory feeds, supporting automated cross-account network inventory but leaving fail-safe orchestration of network API changes unmet.
C:This approach reconciles desired configuration without repeatedly creating duplicate resources; blind create calls can generate unnecessary objects on retries, which helps with repeatable safe network API automation instead of delivering fail-safe orchestration of network API changes.
D:This alternative retrieves configured route entries for a testable deployment assertion; a ping test cannot reliably expose which route entry matched, so it addresses machine-checkable routing-state verification rather than the required fail-safe orchestration of network API changes.
Question 422
A transport team needs to understand which BGP prefixes a particular Transit Gateway route analysis path follows. What is the best next configuration decision?
- Separate topology registration from actual network route configuration
- Use Transit Gateway Route Analyzer where supported
- Use AWS Network Manager topology views for registered global networks
- Use Network Manager monitoring with relevant CloudWatch-backed metrics
Explanation
Correct Answer
B:The approach evaluates a modeled routing path through transit gateway route tables; a general health-check probe does not describe transit route resolution, directly enabling transit-layer path assessment between attachments in this situation.
Incorrect Answers
A:This alternative distinguishes management inventory from data-plane forwarding; adding a device to a topology map does not establish TGW or VPC routes, so it addresses correct operations model for managed network topology rather than the required transit-layer path assessment between attachments.
C:The proposed action displays managed global network resources and connections; a single VPC subnet route list lacks the global context, supporting visibility into multi-Region WAN attachment relationships but leaving transit-layer path assessment between attachments unmet.
D:This approach aggregates WAN and AWS network telemetry across managed connections; individual interface packet captures do not provide a persistent WAN health overview, which helps with consolidated operational status for global links instead of delivering transit-layer path assessment between attachments.
Question 423
A company needs to know whether traffic is being dropped at a Transit Gateway attachment during a load test. Which action directly resolves the stated problem?
- Capture time-series CloudWatch metrics and scheduled active network measurements
- Enable AWS Network Firewall logging and supported monitoring metrics
- Monitor Site-to-Site VPN TunnelState and related metrics
- Examine Transit Gateway metrics such as packet drop counters
Explanation
Correct Answer
D:The approach tracks traffic and drop behavior at the gateway service; DNS query logs cannot measure packet loss at a transit attachment, directly enabling quantitative transit-path troubleshooting in this situation.
Incorrect Answers
A:This approach establishes normal performance ranges for later regression comparisons; a one-time route-table export does not measure time-varying network behavior, which helps with baseline throughput and latency during healthy operations instead of delivering quantitative transit-path troubleshooting.
B:This alternative emits traffic inspection and alert information from firewall processing; VPC Flow Logs cannot expose the complete rule context of a stateful firewall, so it addresses visibility into inspected flow decisions rather than the required quantitative transit-path troubleshooting.
C:Although this setting reports AWS-side tunnel condition over time for alerting, an ELB target-health metric tracks application targets rather than IPsec tunnels; this concerns evidence of VPN tunnel reliability, not the specified quantitative transit-path troubleshooting.
Question 424
A regional office uses a dynamic BGP-capable firewall and wants AWS-provided learned routes over its VPN. What is the best next configuration decision?
- Attach Site-to-Site VPN to AWS Transit Gateway
- Select an accelerated Site-to-Site VPN attachment where supported
- Terminate the Site-to-Site VPN on the VPC's virtual private gateway
- Configure a dynamic Site-to-Site VPN with BGP-capable customer gateway
- Deploy AWS Site-to-Site VPN over the internet
Explanation
Correct Answer
D:This configuration exchanges routes dynamically over the VPN tunnel sessions; static route-only VPN connections require route changes to be maintained explicitly, so it delivers adaptive route learning between branch and AWS under the stated constraints.
Incorrect Answers
A:The proposed action uses the transit routing hub to exchange routes between VPN and selected attachments; isolation still depends on transit gateway route-table design, supporting centralized hybrid routing for multiple networks but leaving adaptive route learning between branch and AWS unmet.
B:This approach uses AWS Global Accelerator to improve the path into AWS VPN endpoints; the feature is not a substitute for a dedicated physical Direct Connect circuit, which helps with accelerated internet-based hybrid VPN ingress instead of delivering adaptive route learning between branch and AWS.
C:This alternative connects the customer gateway IPsec service to the VPC routing boundary; a TGW becomes more appropriate for many separately attached VPCs, so it addresses VPC-specific managed VPN termination rather than the required adaptive route learning between branch and AWS.
E:The proposed action creates IPsec tunnels between customer gateway and AWS VPN termination; internet-path latency and variability remain relevant to SLA planning, supporting rapid encrypted hybrid connectivity over existing internet access but leaving adaptive route learning between branch and AWS unmet.
Question 425
A CloudFront distribution needs a custom alternate domain name using an ACM certificate. Which AWS networking approach meets this constraint?
- Use an eligible ACM certificate in us-east-1 for the CloudFront viewer TLS configuration
- Configure ALB mutual TLS with an appropriate trust store
- Request and attach an AWS Certificate Manager public certificate to the HTTPS listener
- Rely on imported third-party certificates in ACM to renew automatically without a replacement process
Explanation
Correct Answer
A:With this choice, the selected action meets CloudFront's certificate-region requirement for custom HTTPS domain names; an otherwise valid certificate in another Region may not be selectable for this distribution, providing valid CDN viewer certificate configuration for the network described.
Incorrect Answers
B:The proposed action authenticates client certificate chains in addition to server-side TLS; a standard HTTPS listener without mTLS does not check a client's certificate identity, supporting authenticated two-way TLS at application ingress but leaving valid CDN viewer certificate configuration unmet.
C:This approach manages supported public certificates for integrated TLS termination; backend services may still need their own TLS settings if end-to-end encryption is required, which helps with managed server identity for ALB client TLS instead of delivering valid CDN viewer certificate configuration.
D:This alternative stores imported third-party certificates for supported service integrations but does not issue or renew them; ACM-managed renewal applies to eligible ACM-issued certificates, not imported certificate material, so it addresses separately managed imported certificate lifecycle rather than the required valid CDN viewer certificate configuration.
Question 426
A public NLB listens for TCP traffic and the platform team wants to restrict allowed source networks. What is the best next configuration decision?
- Combine supported AWS Shield protections with WAF at the eligible web entry points
- Apply appropriate NLB security-group and backend network controls where supported
- Place the application behind an approved identity-aware access proxy or VPN
- Expose the service through PrivateLink endpoint-service access
Explanation
Correct Answer
B:This configuration limits permitted transport connections according to source network policy; WAF is not natively an arbitrary TCP payload firewall for an NLB, so it delivers restricted layer-four public ingress under the stated constraints.
Incorrect Answers
A:This alternative applies complementary network-scale and HTTP request threat mitigations; a single subnet ACL cannot inspect both global floods and web attack signatures, so it addresses layered perimeter resilience for public services rather than the required restricted layer-four public ingress.
C:The proposed action requires authenticated access before sensitive network endpoints are reachable; allowing the entire internet CIDR through a security group does not meet access control intent, supporting authenticated administrative ingress isolation but leaving restricted layer-four public ingress unmet.
D:This approach creates an approved private interface endpoint path from consumer VPCs; an internet-facing ALB would still expose a public endpoint, which helps with partner-specific private application ingress instead of delivering restricted layer-four public ingress.
Question 427
A network automation Lambda can modify any security group but only needs one tagged group in a workload account. What is the most suitable design or configuration?
- Narrow its IAM permissions and resource conditions where supported
- Use CloudFormation StackSets with organizational deployment targets
- Assume scoped cross-account IAM roles using STS during deployment
- Apply appropriate stack termination protection and resource deletion policies
Explanation
Correct Answer
A:This configuration limits API changes to the resources and operations required by the function; broad wildcard permissions increase the impact of bugs or compromised automation, so it delivers least-privilege network remediation automation under the stated constraints.
Incorrect Answers
B:This alternative deploys a consistent stack across selected accounts and Regions; an individual stack exists in one account and Region instead of the whole target fleet, so it addresses centrally distributed network logging baseline rather than the required least-privilege network remediation automation.
C:Although this setting grants temporary least-privilege credentials in the destination account, embedding access keys into pipeline code creates an avoidable secret-management risk; this concerns controlled multi-account IaC execution, not the specified least-privilege network remediation automation.
D:The proposed action guards selected deployed networking infrastructure from unintended teardown; IAM alone may not express the desired per-resource retention behavior during stack updates, supporting protected lifecycle of critical network resources but leaving least-privilege network remediation automation unmet.
Question 428
An investigator must obtain historical VPC Flow Log records identifying denied TCP conversations to an EC2 listener, then inspect actual packet-level TLS handshake details for the same workload. Which evidence sources are appropriate? Choose TWO.
- Parse the configured VPC Flow Log fields for the accepted/rejected conversations
- Use VPC Traffic Mirroring or another packet-capture location
- Customize the VPC Flow Logs format to include supported extended fields
- Check Flow Logs limitations for traffic to the AmazonProvidedDNS resolver
- Investigate the applicable security group or NACL control first
Explanation
Correct Answers
A:This component uses logged five-tuple and metadata for network-flow correlation; a CloudTrail management event is not a per-connection traffic record, contributing protocol and endpoint identification within flow logs to the combined requirement for protocol and endpoint identification within flow logs and packet contents beyond flow metadata.
B:This component captures supported packet payloads for protocol-level analysis; ACCEPT records do not include TLS cipher negotiation details, contributing packet contents beyond flow metadata to the combined requirement for protocol and endpoint identification within flow logs and packet contents beyond flow metadata.
Incorrect Answers
C:This alternative records additional origin and destination information for relevant network address translation contexts; ordinary default fields may reflect observation-interface addresses rather than original packet endpoints, so it addresses deeper source/destination flow attribution rather than the required protocol and endpoint identification within flow logs and packet contents beyond flow metadata.
D:Although this setting recognizes that certain AWS-reserved service traffic is excluded from standard flow logging, absence of a record is not conclusive proof that the DNS query never occurred; this concerns correct interpretation of a flow-log visibility gap, not the specified protocol and endpoint identification within flow logs and packet contents beyond flow metadata.
E:The proposed action identifies a captured packet flow denied by AWS network filtering; no HTTP server log can explain a request blocked before reaching the host, supporting network-control cause of rejected traffic but leaving protocol and endpoint identification within flow logs and packet contents beyond flow metadata unmet.
Question 429
A media origin sends an identical file separately to each worldwide customer and saturates its outbound link. Which change is the most appropriate?
- Check multicast domain associations, source registration and receiver membership
- Register compatible multicast sources and members against the TGW multicast domain
- Keep targeted unicast transport to the distinct destinations
- Use Transit Gateway multicast where supported and correctly configure membership
- Place cacheable delivery behind CloudFront
Explanation
Correct Answer
E:This configuration serves repeated HTTP objects from edge caches rather than repeatedly fetching the origin; raw IP multicast is not a supported replacement for public web CDN distribution, so it delivers efficient one-to-many HTTP content delivery under the stated constraints.
Incorrect Answers
A:Although this setting verifies multicast-specific configuration beyond normal IP unicast routes, a TGW unicast route alone does not join a multicast group; this concerns active receiver enrollment and multicast forwarding, not the specified efficient one-to-many HTTP content delivery.
B:The proposed action establishes the designated sender and receiver bindings; receivers must join or be registered under the selected multicast model, supporting functioning group-delivery distribution but leaving efficient one-to-many HTTP content delivery unmet.
C:This approach sends separate messages when every receiver has different data; multicast replication is valuable only when multiple receivers should get the same content, which helps with recipient-specific delivery semantics instead of delivering efficient one-to-many HTTP content delivery.
D:This alternative replicates multicast group traffic to registered receivers through supported transit multicast domains; ordinary VPC unicast does not automatically replicate to an IP multicast group, so it addresses one-to-many multicast stream delivery rather than the required efficient one-to-many HTTP content delivery.
Question 430
A primary regional endpoint is degraded and the organization wants managed DNS to return a secondary Region. Which action directly resolves the stated problem?
- Maintain enough spare target capacity and Auto Scaling limits in surviving AZs
- Use Global Accelerator health-based regional endpoint routing
- Use Route 53 failover records with a reliable health signal
- Distribute load-balancer targets across multiple enabled Availability Zones
Explanation
Correct Answer
C:The approach changes authoritative DNS answers according to health evaluation; recursive resolver caching can delay the change experienced by users, directly enabling DNS-driven regional failover in this situation.
Incorrect Answers
A:This alternative reserves scaling headroom for zonal failover demand; a functioning load balancer cannot process requests the remaining application nodes cannot handle, so it addresses sufficient post-failure compute capacity rather than the required DNS-driven regional failover.
B:Although this setting steers flows using anycast ingress and endpoint health, preserving active connection state remains an application-level concern; this concerns rapid global failover independent of DNS cache turnover, not the specified DNS-driven regional failover.
D:This approach provides independent zonal compute capacity behind a managed endpoint; two instances in one subnet do not tolerate that subnet's AZ outage, which helps with high availability across regional AZ failure domains instead of delivering DNS-driven regional failover.