Route53 Flashcards

1
Q

What is DNS?

A

Used to create human-friendly website names to IP addresses.

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2
Q

What are the two different common forms of IP?

A

IPv4 - 32 bit field which has over 4 billion addresses. A signal grain of sand for each would fill up a dump truck.

IPv6 - 128 bit field which has 340 undecillion addresses. A signal grain of sand for each would fill up the sun.

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3
Q

When looking at domain names, what is the top level domain vs the second level domain?

A

The top level domain is the last word in the domain name. The second level, if there is one, is the word before that

  • cnn.com - top level: .com; no second level
  • bbc.co.uk - top level: .uk; second level: .co
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4
Q

True or False. Elastic Load balancers never have a pre-defined IPv4 address. You resolve them using a DNS name.

A

True.

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5
Q

What are common DNS types? List 6

A
  • SOA Records
  • NS Records
  • A Records
  • CNAMES
  • MX Records
  • PTR Records
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6
Q

True or False. You cannot buy domain names with AWS.

A

False, you can.

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7
Q

True or False. It can take up to 5 days to register a domain depending on the circumstances.

A

False, it can take up to 3 days.

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8
Q

What is a simple routing policy?

A

Only have one record with multiple IP addresses. If you specify multiple values in a record, Route 53 returns all values to the user in random order.

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9
Q

What is weighted routing policy and how does it work?

A

Allows you to split your traffic to different regions of the world, depending on the percentages you’ve created.

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10
Q

What is latency based routing and how does it work?

A

Route 53 determines which is the routing policy with the lowest latency (fastest response time) and then sends the user to that server.

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11
Q

What is failover routing policy and how does it work?

A

You choose an active and passive server. When the active fails a healthcheck, it fails over to the passive server.

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12
Q

What is geolocation routing policy and how does it work?

A

Based on where the DNS for the customer shows them, the routing policy will route the customer to the necessary EC2 in the correct region.

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13
Q

What is a multivalue answer policy and how does it work?

A

Allows you to configure Route 53 to return multiple values, such as IP addresses for your web serves, in response to DNS queries. Basically simple routing policy with the ability for a healthcheck.

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14
Q

What is the difference between an Alias Record and a CNAME?

A

Alias record directly links, the CNAME uses a lookup to reference the link. The primary difference between a CNAME record and an ALIAS record is not in the result—both record types point to another DNS record—but in how they resolve the target DNS record when queried. In short, one (ALIAS record) is safe to use at the zone apex (ex. naked domain, such as example.com) and the other is not.

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15
Q

You have created a new subdomain for your popular website, and you need this subdomain to point to an Elastic Load Balancer using Route53. Which DNS record set should you create?

  • A
  • CNAME
A

CNAME

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16
Q

True or False: There is a limit to the number of domain names that you can manage using Route 53.

A

True and False. With Route 53 there is a default limit of 50 names. However, this limit can be increased by contacting AWS Support.

17
Q

Your company hosts 10 web servers all serving the same web content in AWS. They want Route 53 to serve traffic to random web servers. Which routing policy will meet this requirement, and provide the best resiliency?

  • Simple Routing
  • Weighted Routing
  • Mutlivalue Routing
  • Latency Routing
A

Multivalue routing lets you configure Amazon Route 53 to return multiple values, such as IP addresses for your web servers, in response to DNS queries. Route 53 responds to DNS queries with up to eight healthy records and gives different answers to different DNS resolvers. The choice of which to use is left to the requesting service effectively creating a form or randomization.

18
Q

What is the difference between geolocation and geoproximity routing?

A

Geolocation routing policy — Use when you want to route traffic based on the location of your users. Geoproximity routing policy — Use when you want to route traffic based on the location of your resources and, optionally, shift traffic from resources in one location to resources in another

19
Q

A company has created a duplicate of its environment in another AWS Region. The application is running in warm standby mode. There is an Application Load Balancer (ALB) in front of the application. Currently, failover is manual and requires updating a DNS alias record to point to the secondary ALB.

How can a solutions architect automate the failover process?

  • Create a latency based routing policy on Amazon Route 53
  • Enable an ALB health check
  • Create a CNAME record on Amazon Route 53 pointing to the ALB endpoint
  • Enable an Amazon Route 53 health check
A

CORRECT: “Enable an Amazon Route 53 health check” is the correct answer.

You can use Route 53 to check the health of your resources and only return healthy resources in response to DNS queries. There are three types of DNS failover configurations:

  1. Active-passive: Route 53 actively returns a primary resource. In case of failure, Route 53 returns the backup resource. Configured using a failover policy.
  2. Active-active: Route 53 actively returns more than one resource. In case of failure, Route 53 fails back to the healthy resource. Configured using any routing policy besides failover.
  3. Combination: Multiple routing policies (such as latency-based, weighted, etc.) are combined into a tree to configure more complex DNS failover.

In this case an alias already exists for the secondary ALB. Therefore, the solutions architect just needs to enable a failover configuration with an Amazon Route 53 health check.

INCORRECT: “Enable an ALB health check” is incorrect. The point of an ALB health check is to identify the health of targets (EC2 instances). It cannot redirect clients to another Region.

INCORRECT: “Create a CNAME record on Amazon Route 53 pointing to the ALB endpoint” is incorrect as an Alias record already exists and is better for mapping to an ALB.

INCORRECT: “Create a latency based routing policy on Amazon Route 53” is incorrect as this will only take into account latency, it is not used for failover.

20
Q

True or False. Route 53 geoproximity routing does not reduce internet latency as well as using Global Accelerator.

A

Tru. GA will direct users to the closest edge location and then use the AWS global network.