You have a load balancer configured for VPC, and all back-end Amazon EC2 instances are in service.
However, your web browser times out when connecting to the load balancer’s DNS name. Which options are
probable causes of this behavior? Choose 2 answers
A.
The load balancer was not configured to use a public subnet with an Internet gateway configured
B.
The Amazon EC2 instances do not have a dynamically allocated private IP address
C.
The security groups or network ACLs are not property configured for web traffic.
D.
The load balancer is not configured in a private subnet with a NAT instance.
E.
The VPC does not have a VGW configured.
A, C
http://www.aiotestking.com/amazon/which-options-are-probable-causes-of-this-behavior/
http://docs.aws.amazon.com/elasticloadbalancing/latest/classic/elb-manage-subnets.html
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A & C.
Reason: Because, here we are using Load Balancer DNS from web browser, so we need either load balancer in Public subnet OR the SG and NACl are not configured properly with Rules which can connect from Internet, then in both the conditions it will fail.
Why not B: because it doesnt matter for ELB whether your EC2 instances have dynamically or statically associated Private IP addresses.
When you register an instance with an elastic network interface (ENI) attached, the load balancer routes requests to the primary IP address of the primary interface (eth0) of the instance.
If your instance is having Dynamic private IP addresses, it will surely cause issue.
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A&C
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Yup…AC
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AC
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