You are managing a legacy application Inside VPC with hard coded IP addresses in its configuration.
Which two mechanisms will allow the application to failover to new instances without the need for
reconfiguration? Choose 2 answers
A.
Create an ELB to reroute traffic to a failover instance
B.
Create a secondary ENI that can be moved to a failover instance
C.
Use Route53 health checks to fail traffic over to a failover instance
D.
Assign a secondary private IP address to the primary ENIO that can be moved to a failover instance
This is an odd question. First of all A cannot be right because ELB does not failover. Cannot be C because Route 53 does work with hard coded IP. Only B & D cannot be rule out so best answer.
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ELB failover can be configured in Route53.
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B,D are the only options.
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I think is
C but not sure about B or D
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I like B and D
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I can’t be D because “You cannot detach a primary network interface from an instance.”
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-eni.html
Creating a secondary ENI will work (because it CAN be moved), and then have an ELB configured to fail over if the instance fails a healthcheck on the primary ENI. Route53 would only check the “hard coded IP” for being healthy which wouldn’t work because the backup instance doesn’t have that IP yet, so it wouldn’t pass the healthcheck either.
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They are not talking about moving primary interface but secondary IP, which is possible.
link(http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-eni.html):
“To ensure failover capabilities, consider using a secondary private IPv4 for incoming traffic on a network interface. In the event of an instance failure, you can move the interface and/or secondary private IPv4 address to a standby instance.”
This question is really confusing, but beautifully explain by someone in mentioned link.
Refer comment section (blahblah)
http://www.aiotestking.com/amazon/which-two-mechanisms-will-allow-the-application-to-failover-to-new-instances-without-the-need-for-reconfiguration-2/
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The link is broken
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What they don’t mention the amount of admin work for the AWS consultant to get this working. So the right answer would be to beat the developer/admin with a fish. Or, in the event you don’t want to go to jail for assault with a fish, B and C are correct.
I want to read these with “once the instance fails.. ”
B. detach the second ENI and attach it to the new instance.
D. remove the SECOND private IP on the primary ENI via api and attach it to the SECOND private IP for the Primary ENI on the new instance.
This is all discussed here:
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-eni.html#create-a-low-budget-high-availability-solution
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B and C
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I agree with B and D.
These are the only options that will allow you to move the hard coded IP address between instances.
ELB and Route 53 only use DNS.
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B, D should be right options!
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/MultipleIP.html#MultipleIPReqs
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B，C
B the second ENI would take the same private IP to the fail over instance.
C Route53 do the fail over without reconfiguration.
You can create an elastic network interface, attach it to an instance, detach it from an instance, and attach it to another instance. The attributes of an elastic network interface follow it as it’s attached or detached from an instance and reattached to another instance. When you move an elastic network interface from one instance to another, network traffic is redirected to the new instance.
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bc
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the question is not clear.
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what is the final answer
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A D
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I go with B and D.
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The key phrases here are “hard-coded IP addresses” and “without the need for reconfiguration” the latter means, no additional networking is required, this removes adding secondary addresses to the already hard-coded addresses in the application. Notice, addresses means, both nodes have a hard-coded IP, which means you do not need a failover IP address, only a means to redirect traffic.
So, you can use the ELB to re-route traffic to healthy instance: A
You can use route53 health checks
A,C
This question does not go on the AWS Greatest Questions DVD to say the least….
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bd
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Correct Answer is B and D
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BD,
elb ip’s cannot be used. You would need to assign new ENIs and assign those hardcoded ip addresses to those ENIs.
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B D – B will move IP- “interface maintains its private IP addresses, Elastic IP addresses, and MAC address”, Still need to move the Secondary Pvt IP- so D.
If you are using B, C is not needed as no DNS change needed – same IP- no change in IP. So C is incompatible with B.
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