AWS Certified Advanced Networking - Specialty ANS-C01 Practice Test 43
Question 420
This AWS networking condition remains unresolved: An internal endpoint for S3 must permit only a specified business bucket although a subnet route to the service is present. What is the MOST direct risk?
- Applying WAF to a public ALB does not make a publicly reachable database private
- Broad allow-all egress increases exfiltration and command-and-control reachability
- Coarse geographic rules without testing can deny legitimate travelers or global partners
- A private S3 gateway route alone does not prevent access to every otherwise allowed bucket
Explanation
Correct Answer
D:A private S3 gateway route alone does not prevent access to every otherwise allowed bucket. The missing control matters because endpoint transport and AWS resource authorization are separate layers. The appropriate corrective action is to configure restrictive VPC endpoint, IAM, and bucket policy conditions as appropriate. To check the outcome, verify that permitted bucket operations succeed and excluded bucket calls fail authorization.
Incorrect Answers
A:Applying WAF to a public ALB does not make a publicly reachable database private can be a real consequence when a multi-tenant application has public load balancers but database instances should never accept internet connections. Here the relevant failure is that a private S3 gateway route alone does not prevent access to every otherwise allowed bucket. The alternative names a different failure mode and does not best account for the stated condition.
B:Broad allow-all egress increases exfiltration and command-and-control reachability can be a real consequence when an audit finds highly permissive outbound SG rules on EC2 instances holding sensitive financial data. Here the relevant failure is that a private S3 gateway route alone does not prevent access to every otherwise allowed bucket. The alternative names a different failure mode and does not best account for the stated condition.
C:Coarse geographic rules without testing can deny legitimate travelers or global partners can be a real consequence when a production ALB must accept only approved client geographies under documented policy while retaining measured business exceptions. Here the relevant failure is that a private S3 gateway route alone does not prevent access to every otherwise allowed bucket. The alternative names a different failure mode and does not best account for the stated condition.
Question 421
An engineer selects the change "Update both tunnel peers to a mutually supported approved IKE and IPsec algorithm suite" because A Site-to-Site VPN has an old cipher suite that is no longer permitted under corporate cryptographic policy. Which technical explanation BEST supports it?
- Encrypted tunnel security depends on negotiated cryptographic properties and policy compatibility
- Certificate lifecycle management covers issuance, renewal, binding and expiration
- DNSSEC signs DNS responses but does not encrypt ordinary resolver requests
- DNSSEC authenticity requires a consistent hierarchical chain and valid signing keys
Explanation
Correct Answer
A:Encrypted tunnel security depends on negotiated cryptographic properties and policy compatibility. This mechanism directly explains why the proposed change, update both tunnel peers to a mutually supported approved IKE and IPsec algorithm suite, fits this particular packet path or control requirement. Without it, leaving deprecated suites enabled may violate governance even if the tunnel stays up. A suitable verification is that a renegotiated tunnel reports only approved algorithms and continues required connectivity.
Incorrect Answers
B:Certificate lifecycle management covers issuance, renewal, binding and expiration explains a different case, for example when a compliance group wants clients to reject an expired ALB certificate before signing into a banking app. In the current topology, the deciding factor is that encrypted tunnel security depends on negotiated cryptographic properties and policy compatibility; this choice therefore does not explain the specified remedy.
C:DNSSEC signs DNS responses but does not encrypt ordinary resolver requests explains a different case, for example when a security team enables Route 53 DNSSEC signing and claims it will hide which domains users query. In the current topology, the deciding factor is that encrypted tunnel security depends on negotiated cryptographic properties and policy compatibility; this choice therefore does not explain the specified remedy.
D:DNSSEC authenticity requires a consistent hierarchical chain and valid signing keys explains a different case, for example when a network team requires DNSSEC verification across a delegated child zone but its validating clients report bogus answers. In the current topology, the deciding factor is that encrypted tunnel security depends on negotiated cryptographic properties and policy compatibility; this choice therefore does not explain the specified remedy.
Question 422
Following remediation of "A new on-premises BIND server is allowed to send queries to Route 53 Resolver inbound endpoint over UDP but TCP responses time out", what evidence MOST directly establishes that it works?
- Independent recursive lookups reach the active Route 53 authoritative name servers
- Large and ordinary DNS queries return successfully from the approved corporate resolver
- External DNSSEC validation succeeds and tampered data is rejected
- Affected VPCs resolve after rule association restoration and the outbound path is healthy
Explanation
Correct Answer
B:Large and ordinary DNS queries return successfully from the approved corporate resolver. This directly tests whether the selected change, permit the required DNS UDP and TCP paths, including large-response fallbacks, achieved the intended network outcome. The key mechanism is that dNS can use TCP for larger responses or retry scenarios as well as UDP. The incident or compliance risk being reduced was that uDP-only validation can hide failures for truncated or large answers.
Incorrect Answers
A:Independent recursive lookups reach the active Route 53 authoritative name servers might confirm another remediation, for instance when a public delegated subdomain has been created in Route 53 but the registrar still delegates only to the old name servers. This question instead requires demonstrating that large and ordinary DNS queries return successfully from the approved corporate resolver. The alternative would not validate the selected network fix.
C:External DNSSEC validation succeeds and tampered data is rejected might confirm another remediation, for instance when a public zone uses DNSSEC but the registrar does not publish the required DS record. This question instead requires demonstrating that large and ordinary DNS queries return successfully from the approved corporate resolver. The alternative would not validate the selected network fix.
D:Affected VPCs resolve after rule association restoration and the outbound path is healthy might confirm another remediation, for instance when a DNS outage affects only a few VPCs after centralized forwarding rule changes. This question instead requires demonstrating that large and ordinary DNS queries return successfully from the approved corporate resolver. The alternative would not validate the selected network fix.
Question 423
During an AWS network design review, the team observes: A data center wants high availability but two VPN tunnels terminate on the same failing customer device. Which solution BEST resolves the gap?
- Use physically diverse Direct Connect connections and redundancy designs meeting the resiliency target
- Run supported IPsec VPN over Direct Connect or encrypt application traffic end to end
- Deploy customer-gateway redundancy with independent routers and tunnel termination paths
- Use a Direct Connect public virtual interface when the public-service routing requirements fit
Explanation
Correct Answer
C:Deploy customer-gateway redundancy with independent routers and tunnel termination paths. The stated configuration and business requirement call for this change because provider-side redundant tunnels do not protect against a shared customer-side device failure. Leaving the existing gap unresolved could mean that relying on dual tunnel count alone leaves one on-premises failure domain. Confirm the improvement by showing that a controlled loss of either customer router leaves an independent hybrid route active.
Incorrect Answers
A:Use physically diverse Direct Connect connections and redundancy designs meeting the resiliency target would address a different scenario, such as when two on-premises data centers require dedicated diverse private circuits to critical AWS Regions. The present issue requires deploy customer-gateway redundancy with independent routers and tunnel termination paths because the network path and control point are different; the alternative does not directly meet this requirement.
B:Run supported IPsec VPN over Direct Connect or encrypt application traffic end to end would address a different scenario, such as when a company must encrypt sensitive hybrid application traffic even though it uses a private Direct Connect circuit. The present issue requires deploy customer-gateway redundancy with independent routers and tunnel termination paths because the network path and control point are different; the alternative does not directly meet this requirement.
D:Use a Direct Connect public virtual interface when the public-service routing requirements fit would address a different scenario, such as when a corporate office needs AWS public service endpoints over a dedicated public routing path without private VPC address exchange. The present issue requires deploy customer-gateway redundancy with independent routers and tunnel termination paths because the network path and control point are different; the alternative does not directly meet this requirement.
Question 424
An AWS network architect encounters this situation: A cross-region Transit Gateway peer shows up but a newly added subnet cannot reach remote service. Which change BEST meets the documented requirement?
- Review supported IKE/IPsec parameters, rekey policy and peer configuration
- Compare advertised and accepted prefixes and restore the intended route policy
- Discover the current endpoint identity and update managed DNS/configuration references
- Add the new subnet CIDR routes on both regional transit tables and VPC route tables
Explanation
Correct Answer
D:Add the new subnet CIDR routes on both regional transit tables and VPC route tables. The stated configuration and business requirement call for this change because transit Gateway peering needs explicit remote prefix routes and per-VPC attachment reachability. Leaving the existing gap unresolved could mean that peering attachment state alone does not propagate all changed VPC prefixes. Confirm the improvement by showing that cross-region probes reach the new subnet and reverse traffic follows approved routes.
Incorrect Answers
A:Review supported IKE/IPsec parameters, rekey policy and peer configuration would address a different scenario, such as when a site VPN fails at regular intervals due to expired or incompatible Internet Key Exchange settings. The present issue requires add the new subnet CIDR routes on both regional transit tables and VPC route tables because the network path and control point are different; the alternative does not directly meet this requirement.
B:Compare advertised and accepted prefixes and restore the intended route policy would address a different scenario, such as when an on-premises application loses access to a VPC after a BGP policy change on the customer Direct Connect router. The present issue requires add the new subnet CIDR routes on both regional transit tables and VPC route tables because the network path and control point are different; the alternative does not directly meet this requirement.
C:Discover the current endpoint identity and update managed DNS/configuration references would address a different scenario, such as when a VPC interface endpoint is deleted and recreated but scripts still target the former endpoint DNS name. The present issue requires add the new subnet CIDR routes on both regional transit tables and VPC route tables because the network path and control point are different; the alternative does not directly meet this requirement.
Question 425
A network review finds: A company set up a gateway endpoint for S3 but forgot to associate it with the subnet's route table. Which consequence MOST clearly explains the need for a fix?
- Creating an endpoint in a VPC does not automatically update unrelated route tables
- A working route in a sibling subnet does not make every subnet connected
- A valid endpoint ENI cannot authorize a consumer whose principal is not permitted
- An egress-only internet gateway does not translate IPv6 clients into IPv4 destinations
Explanation
Correct Answer
A:Creating an endpoint in a VPC does not automatically update unrelated route tables. The missing control matters because gateway endpoints use route table prefix-list entries for supported regional AWS services. The appropriate corrective action is to associate the S3 gateway endpoint with the required VPC route tables and policies. To check the outcome, verify that subnet traffic to S3 uses the endpoint target with no public NAT dependency.
Incorrect Answers
B:A working route in a sibling subnet does not make every subnet connected can be a real consequence when a service team has two private subnets but one subnet has no route toward the shared Transit Gateway. Here the relevant failure is that creating an endpoint in a VPC does not automatically update unrelated route tables. The alternative names a different failure mode and does not best account for the stated condition.
C:A valid endpoint ENI cannot authorize a consumer whose principal is not permitted can be a real consequence when a provider account restricts PrivateLink endpoint-service connections but a new consumer account still cannot connect. Here the relevant failure is that creating an endpoint in a VPC does not automatically update unrelated route tables. The alternative names a different failure mode and does not best account for the stated condition.
D:An egress-only internet gateway does not translate IPv6 clients into IPv4 destinations can be a real consequence when a VPC with IPv6-only workloads must reach IPv4-only endpoints while NAT64 support is not configured. Here the relevant failure is that creating an endpoint in a VPC does not automatically update unrelated route tables. The alternative names a different failure mode and does not best account for the stated condition.
Question 426
For the scenario "A team wants to minimize inter-Region data charges for a global workload with frequent large cross-region responses", the proposed response is "Place computation and cache near user demand while modeling regional replication needs". Which network behavior makes this suitable?
- EC2 network throughput ceilings vary by instance family and workload pattern
- Cross-Region transfer and origin placement affect both latency and billed data movement
- EFA offers specialized low-latency networking for eligible HPC workloads
- Pod networking consumption can constrain density before compute cores are exhausted
Explanation
Correct Answer
B:Cross-Region transfer and origin placement affect both latency and billed data movement. This mechanism directly explains why the proposed change, place computation and cache near user demand while modeling regional replication needs, fits this particular packet path or control requirement. Without it, sending every read across Regions can waste bandwidth despite local available replicas. A suitable verification is that cost and latency profiles improve when reads are served within the permitted Region.
Incorrect Answers
A:EC2 network throughput ceilings vary by instance family and workload pattern explains a different case, for example when a batch data service saturates one EC2 network path because instances were placed on incompatible network tiers. In the current topology, the deciding factor is that cross-Region transfer and origin placement affect both latency and billed data movement; this choice therefore does not explain the specified remedy.
C:EFA offers specialized low-latency networking for eligible HPC workloads explains a different case, for example when an HPC application needs low-latency communication among tightly coupled EC2 nodes. In the current topology, the deciding factor is that cross-Region transfer and origin placement affect both latency and billed data movement; this choice therefore does not explain the specified remedy.
D:Pod networking consumption can constrain density before compute cores are exhausted explains a different case, for example when a shared VPC runs out of available ENIs and VPC addresses as its EKS worker fleet scales. In the current topology, the deciding factor is that cross-Region transfer and origin placement affect both latency and billed data movement; this choice therefore does not explain the specified remedy.
Question 427
A team chooses to Choose Gateway Load Balancer with appliance targets and service insertion endpoints after observing: A fleet of virtual firewalls must receive traffic with flow symmetry and transparent appliance insertion. Which result would BEST verify the change?
- Paths and hosts reach intended target groups while WAF test requests are blocked
- An approved Ingress change creates the intended listener and target group consistently
- Bidirectional flow traces pass the intended inspection appliance without bypass
- Targets transition healthy on the intended probe and real user requests succeed
Explanation
Correct Answer
C:Bidirectional flow traces pass the intended inspection appliance without bypass. This directly tests whether the selected change, choose Gateway Load Balancer with appliance targets and service insertion endpoints, achieved the intended network outcome. The key mechanism is that gateway Load Balancer uses GENEVE to distribute network flows to security appliance targets. The incident or compliance risk being reduced was that a normal HTTP ALB is not a drop-in transparent inspection hop for arbitrary IP packets.
Incorrect Answers
A:Paths and hosts reach intended target groups while WAF test requests are blocked might confirm another remediation, for instance when a web application needs path routing, HTTP host rules, and WAF inspection for incoming requests. This question instead requires demonstrating that bidirectional flow traces pass the intended inspection appliance without bypass. The alternative would not validate the selected network fix.
B:An approved Ingress change creates the intended listener and target group consistently might confirm another remediation, for instance when an EKS platform needs Kubernetes Ingress-driven creation of an ALB across cluster namespaces. This question instead requires demonstrating that bidirectional flow traces pass the intended inspection appliance without bypass. The alternative would not validate the selected network fix.
D:Targets transition healthy on the intended probe and real user requests succeed might confirm another remediation, for instance when a batch service runs healthy processes but fails ALB health checks because the probe path requires a user login. This question instead requires demonstrating that bidirectional flow traces pass the intended inspection appliance without bypass. The alternative would not validate the selected network fix.
Question 428
The team addressed this problem: An attached spoke VPC cannot reach another spoke despite both attachments being Available on a Transit Gateway. Which observation BEST demonstrates the required result?
- Reachability tests prove allowed spokes connect while sensitive-to-audit traffic is blocked
- The owner updates routes while the participant deploys supported workload resources
- An approved download succeeds and the private instance has no public-address requirement
- The correct target attachment appears in the evaluated route path for both directions
Explanation
Correct Answer
D:The correct target attachment appears in the evaluated route path for both directions. This directly tests whether the selected change, add the intended Transit Gateway association and route propagation or static routes on the correct route tables, achieved the intended network outcome. The key mechanism is that transit Gateway attachments and route tables control forwarding independently of attachment health. The incident or compliance risk being reduced was that available attachments without suitable routes do not permit transit connectivity.
Incorrect Answers
A:Reachability tests prove allowed spokes connect while sensitive-to-audit traffic is blocked might confirm another remediation, for instance when a shared Transit Gateway route table receives propagated spokes but a sensitive subnet must never see the audit VPC. This question instead requires demonstrating that the correct target attachment appears in the evaluated route path for both directions. The alternative would not validate the selected network fix.
B:The owner updates routes while the participant deploys supported workload resources might confirm another remediation, for instance when an AWS organization has a shared VPC but a participant account cannot edit the subnet route table it does not own. This question instead requires demonstrating that the correct target attachment appears in the evaluated route path for both directions. The alternative would not validate the selected network fix.
C:An approved download succeeds and the private instance has no public-address requirement might confirm another remediation, for instance when a team uses a NAT gateway for private-subnet internet access but the private subnet route points to an internet gateway directly. This question instead requires demonstrating that the correct target attachment appears in the evaluated route path for both directions. The alternative would not validate the selected network fix.
Question 429
For this networking situation, An existing subnet exhausts IPv4 addresses during a rapid Auto Scaling expansion, the team applies "Allocate and associate an appropriate additional VPC CIDR and subnet capacity". Which validation is strongest?
- A new scale-out event launches successfully with documented free-IP headroom
- A throughput benchmark improves after matching instance and driver capabilities
- A controlled multicast publisher reaches subscribed eligible AWS consumers
- Bidirectional large transfers complete without excess retransmits at the approved MTU
Explanation
Correct Answer
A:A new scale-out event launches successfully with documented free-IP headroom. This directly tests whether the selected change, allocate and associate an appropriate additional VPC CIDR and subnet capacity, achieved the intended network outcome. The key mechanism is that subnet free IP capacity constrains launches and network interface assignment. The incident or compliance risk being reduced was that increasing Auto Scaling desired capacity without new addresses may leave instances Pending.
Incorrect Answers
B:A throughput benchmark improves after matching instance and driver capabilities might confirm another remediation, for instance when a data-intensive EC2 workload has poor network throughput because its instance family lacks enhanced networking features. This question instead requires demonstrating that a new scale-out event launches successfully with documented free-IP headroom. The alternative would not validate the selected network fix.
C:A controlled multicast publisher reaches subscribed eligible AWS consumers might confirm another remediation, for instance when a company wants to receive multicast from on premises into AWS applications but its current peering design lacks required support. This question instead requires demonstrating that a new scale-out event launches successfully with documented free-IP headroom. The alternative would not validate the selected network fix.
D:Bidirectional large transfers complete without excess retransmits at the approved MTU might confirm another remediation, for instance when a client sends very large packets through a network path containing VPC, VPN and an on-premises firewall with different MTUs. This question instead requires demonstrating that a new scale-out event launches successfully with documented free-IP headroom. The alternative would not validate the selected network fix.
Question 430
Following remediation of "A company adds a second regional Transit Gateway but leaves old branch route filters active", what evidence MOST directly establishes that it works?
- BGP and route-table views restore the intended VPC prefix with working round-trip probes
- Corporate route tables include the new Region and traffic follows its approved path
- A test principal accesses allowed objects and rejected operations retain clear error evidence
- Loss of either customer device leaves a permitted independent route active
Explanation
Correct Answer
B:Corporate route tables include the new Region and traffic follows its approved path. This directly tests whether the selected change, update hybrid route advertisements and central gateway route tables for the new Region, achieved the intended network outcome. The key mechanism is that transit route design needs propagated or static prefixes on both cloud and customer boundaries. The incident or compliance risk being reduced was that a functioning new regional attachment is useless without branch visibility of its CIDRs.
Incorrect Answers
A:BGP and route-table views restore the intended VPC prefix with working round-trip probes might confirm another remediation, for instance when an on-premises application loses access to a VPC after a BGP policy change on the customer Direct Connect router. This question instead requires demonstrating that corporate route tables include the new Region and traffic follows its approved path. The alternative would not validate the selected network fix.
C:A test principal accesses allowed objects and rejected operations retain clear error evidence might confirm another remediation, for instance when an organization uses VPC endpoints for private S3 access but an endpoint policy now rejects a required object operation. This question instead requires demonstrating that corporate route tables include the new Region and traffic follows its approved path. The alternative would not validate the selected network fix.
D:Loss of either customer device leaves a permitted independent route active might confirm another remediation, for instance when a customer configures redundant links but a single customer gateway remains the only advertised next hop. This question instead requires demonstrating that corporate route tables include the new Region and traffic follows its approved path. The alternative would not validate the selected network fix.