Amazon ANS-C01 Practice Test - Questions Answers, Page 8
List of questions
Question 71
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Your company runs an application for the US market in the us-east-1 AWS region. This application uses proprietary TCP and UDP protocols on Amazon Elastic Compute Cloud (EC2) instances. End users run a real-time, front-end application on their local PCs. This front-end application knows the DNS hostname of the service.
You must prepare the system for global expansion. The end users must access the application with lowest latency.
How should you use AWS services to meet these requirements?
Question 72
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You deploy an Amazon EC2 instance that runs a web server into a subnet in a VPC. An Internet gateway is attached, and the main route table has a default route (0.0.0.0/0) configured with a target of the Internet gateway.
The instance has a security group configured to allow as follows:
Protocol: TCP
Port: 80 inbound, nothing outbound
The Network ACL for the subnet is configured to allow as follows:
Protocol: TCP
Port: 80 inbound, nothing outbound
When you try to browse to the web server, you receive no response.
Which additional step should you take to receive a successful response?
Explanation:
To enable the connection to a service running on an instance, the associated network ACL must allow both inbound traffic on the port that the service is listening on as well as allow outbound traffic from ephemeral ports. When a client connects to a server, a random port from the ephemeral port range (1024-65535) becomes the client's source port. The designated ephemeral port then becomes the destination port for return traffic from the service, so outbound traffic from the ephemeral port must be allowed in the network ACL. https://aws.amazon.com/premiumsupport/knowledgecenter/ resolve-connection-sg-acl-inbound/
Question 73
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An organization launched an IPv6-only web portal to support IPv6-native mobile clients. Front-end instances launch in an Amazon VPC associated with an appropriate IPv6 CIDR. The VPC IPv4 CIDR is fully utilized. A single subnet exists in each of two Availability Zones with appropriately configured IPv6 CIDR associations. Auto Scaling is properly configured, and no Elastic Load Balancing is used.
Customers say the service is unavailable during peak load times. The network engineer attempts to launch an instance manually and receives the following message: “There are not enough free addresses in subnet ‘subnet-12345677’ to satisfy the requested number of instances.” What action will resolve the availability problem?
Question 74
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An organization is replacing a tape backup system with a storage gateway. there is currently no connectivity to AWS. Initial testing is needed.
What connection option should the organization use to get up and running at minimal cost?
Question 75
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All IP addresses within a 10.0.0.0/16 VPC are fully utilized with application servers across two Availability Zones. The application servers need to send frequent UDP probes to a single central authentication server on the Internet to confirm that is running up-to-date packages. The network is designed for application servers to use a single NAT gateway for internal access. Testing reveals that a few of the servers are unable to communicate with the authentication server.
Explanation:
Ref: https://docs.aws.amazon.com/vpc/latest/userguide/vpc-nat-gateway.html"A NAT gateway can support up to 55,000 simultaneous connections to each unique destination. Thislimit also applies if you create approximately 900 connections per second to a single destination (about 55,000 connections per minute). If the destination IP address, the destination port, or the protocol (TCP/UDP/ICMP) changes, you can create an additional 55,000 connections. For more than 55,000 connections, there is an increased chance of connection errors due to port allocation errors.
These errors can be monitored by viewing the ErrorPortAllocation CloudWatch metric for your NAT gateway. For more information, see Monitoring NAT Gateways Using Amazon CloudWatch."
Question 76
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An organization is using a VPC endpoint for Amazon S3. When the security group rules for a set of instances were initially configured, access was restricted to allow traffic only to the IP addresses of the Amazon S3 API endpoints in the region from the published JSON file. The application was working properly, but now is logging a growing number of timeouts when connecting with Amazon S3. No internet gateway is configured for the VPC.
Which solution will fix the connectivity failures with the LEAST amount of effort?
Explanation:
https://aws.amazon.com/blogs/aws/subscribe-to-aws-public-ip-address-changes-via-amazon-sns/
Question 77
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A bank built a new version of its banking application in AWS using containers that content to an onpremises database over VPN connection. This application version requires users to also update their client application. The bank plans to deprecate the earlier client version. However, the company wants to keep supporting earlier clients through their on-premises version of the application to serve a small portion of the customers who haven’t yet upgraded.
What design will allow the company to serve both newer and earlier clients in the MOST efficient way?
Question 78
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A company is deploying a non-web application on an AWS load balancer. All targets are servers located on-premises that can be accessed by using AWS Direct Connect. The company wants to ensure that the source IP addresses of clients connecting to the application are passed all the way to the end server.
How can this requirement be achieved?
Explanation:
https://docs.aws.amazon.com/elasticloadbalancing/latest/network/load-balancer-targetgroups.html#proxy-protocol
Question 79
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An AWS CloudFormation template is being used to create a VPC peering connection between two existing operational VPCs, each belonging to a different AWS account. All necessary components in the ‘Remote’ (receiving) account are already in place.
The template below creates the VPC peering connection in the Originating account. It contains these components:
AWSTemplateFormation Version: 2010-09-09
Parameters:
Originating VCId:
Type: String
RemoteVPCId:
Type: String
RemoteVPCAccountId:
Type: String
Resources: newVPCPeeringConnection:
Type: ‘AWS::EC2::VPCPeeringConnection’
Properties:
VpcdId: !Ref OriginatingVPCId
PeerVpcId: !Ref RemoteVPCId
PeerOwnerId: !Ref RemoteVPCAccountId
Which additional AWS CloudFormation components are necessary in the Originating account to create an operational cross-account VPC peering connection with AWS CloudFormation? (Select two.)
Explanation:
https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/AWS_EC2.html
Question 80
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A Network Engineer is provisioning a subnet for a load balancer that will sit in front of a fleet of application servers in a private subnet. There is limited IP space left in the VPC CIDR. The application has few users now but is expected to grow quickly to millions of users.
What design will use the LEAST amount of IP space, while allowing for this growth?
Explanation:
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