Route 53 Flashcards by Jana Dohman

What is DNS?

DNS is used to convert human-friendly domain names (http://acloud.guru) into an Internet Protocol (IP) address (http://82.124.53.1).

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What are the two common forms of IP addresses that Route 53 supports?

IPv4 and IPv6

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What is an IPv4 IP address?

The IPv4 space is a 32-bit field and has over 4 billion different addresses (4,294,967,296)

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What is an IPv6 address?

The IPv6 space is a 128-bit field that has over 340 undecillion different addresses

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What is a top-level domain name?

The last word in a domain name (e.g. “com” of google.com, “guru” of acloud.guru)

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What is the second-level domain name?

The second to last work in a domain name and is optional (e.g. “co” of bbc.co.uk)

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Who controls the top-level domain names?

The Internet Assigned Numbers Authority (IANA) in a root zone database (http://www.iana.org/domains/root/db)

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What is a domain registrar?

An authority that can assign domain names directly under one or more top-level domains.
These domains are registered with InterNIC, a service of ICANN, which enforces uniqueness of domain names across the internet.

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Where do domain names get registered?

With InterNIC, a service of ICANN, which enforces uniqueness of domain names across the internet, and are stored in the WHOIS database

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What does the SOA record in DNS store?

It is the “Start of Authority” record and it stores:
1. The name of the server that supplied the data for the zone
2. The administrator of the zone
3. The current version of the data file
4. The default number of seconds for the time-to-live file on resource records

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What does the NS records in DNS used for?

It is the “Name Server” record and they are used by top-level domain servers to direct traffic to the content DNS server that contains the authoritative DNS records.

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What is an A record in DNS?

An A (or Address) record is the fundamental type of DNS record, and is used by a computer to translate the name of the domain into an IP address.

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What is TTL in DNS?

The length that a DNS record is cached on either the revolving server or the user’s own local PC is equal to the value of the TTL (time to live) in seconds.

The lower the time to live, the faster changes to DNS records take to propagate throughout the internet.

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What is a CNAME record in DNS?

A CNAME (canonical name) record can be used to resolve one domain from another. For example, you may have a mobile website with the domain name http://m.acloud.guru and a CNAME can be used to point http://mobile.acloud.guru to http://m.acloud.guru.

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What are Alias records in DNS?

Alias records are used to map resource record sets in your hosted zone to load balancers, CloudFront distributions, or S3 buckets that are configured as websites.

Alias records work as CNAME records in that you can map one DNS name (www.example.com) to another target DNS name (elb1234.elb.amazonaws.com).

Only a concept in AWS.

They can be used for naked domain names (zone apex records, like http://acloud.guru).

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What are the limitations of CNAME records in DNS?

They cannot be used for naked domain names (zone apex record, like http://acloud.guru)

What are the seven different routing policies available in Route 53?

Simple Routing
Weighted Routing
Latency-Based Routing
Failover Routing
Geolocation Routing
Geoproximity Routing (Traffic Flow Only)
Multivalue Answer Routing

What is the difference between an Alias record and a CNAME record in DNS?

CNAME and Alias records map one one domain to another but CNAME records cannot be used for naked domain names (zone apex records, like http://acloud.guru). Alias records are only a concept in Route 53, and not in DNS in general.

If you are given a scenario-based question where you are given the choice between an Alias record vs a CNAME record for anything to do with AWS, which should you choose?

Alias record

What are the common DNS record types?

SOA records (State of Authority records), where DNS starts
CNAME records (Canonical Name records), maps one domain name to another
NS records (Name Server records), where is the DNS information stored?
A records (Address records), maps domain name back to IP address

Can you register a domain name with AWS?

Yes, in Route 53, but it can take up to three days to register, depending on the circumstances.

What is Simple Routing Policy in Route 53?

You can have one record with multiple IP addresses. If you specify multiple IP addresses in the same record, Route 53 returns all of them to the user in random order.

What is Weighted Routing Policy in Route 53?

Allows you to split your traffic based on different weights assigned (e.g. set 10% of your traffic to go to us-east-1 and 90% to eu-west-1).

How can you use health checks with Route 53?

You can set health checks on individual record sets, and you can also set health checks on individual weightings in a Weighted Routing Policy.

If a record fails a health check, it will be removed from Route 53 until it passes the health check.

You can set up SNS notifications to alert you about failed health checks.

If you are given a scenario where it asks about sending a certain amount of your traffic to specific regions, what routing policy would you recommend?

Weighted Routing Policy

What is Failover Routing Policy in Route 53?

Failover Routing Policies are used when you want to set up an active/passive set-up (e.g. you want your primary site to be in eu-west-2 and your secondary DR site in ap-southeast-2). Route 53 will monitor the health of your primary site using a health check.

If you are given a scenario that is talking about active/passive related to routing in Route 53, what routing policy would you recommend?

Failover Routing Policy

If you are given a scenario that is talking about failover requirements related to routing in Route 53, what routing policy would you recommend?

Failover Routing Policy

What is Geolocation Routing Policy in Route 53?

Lets you choose where your traffic will be sent based on the geographic location of your users (i.e. the location from which DNS queries originate), sometimes for localization purposes.

If you are given an scenario where customers are based in different parts of the world and you need to control where you send them based on their end location, what routing policy in Route 53 would you recommend?

Geolocation Routing Policy

If you are given a scenario where it is talking about the location of users and you need to send them to a particular location for regulatory requirements rather than latency, what routing policy in Route 53 would you recommend?

Geolocation Routing Policy

What is Geoproximity Routing Policy in Route 53 (traffic flow only)?

Geoproximity Routing lets Amazon Route 53 route traffic to your resources based on the geographic location of your users and your resources. You can also optionally choose to route more traffic or less to a given resource by specifying a value, known as a bias.

What is Route 53 Traffic Flow?

You can use Route 53 Traffic Flow to build a routing system that uses a combination of: * geographic location * latency * availability to route traffic from your users to your cloud or on-premises endpoints. You can build your routing policies from scratch or from a template from a library and then customize it.

What is a "bias" in Route 53 routing?

It is related to Geoproximity Routing and it is a value that can be specified to optionally choose to route more traffic or less to a given resource. It expands or shrinks the size of the geographic region from which the traffic is routed to a resource.

To use Geoproximity Routing, what must you have set up?

Route 53 Traffic Flow

What is Latency-Based Routing Policy in Route 53?

Allows you to route your traffic based on the lowest network latency for your end user (i.e. the region that will give them the fasted response time). To use Latency-Based Routing, you create a latency resource record set for the EC2 (or ELB) resource in that region that hosts your website. When Route 53 receives a query for your site, it selects the latency resource record set for the region that gives the user the lowest latency. Route 53 then response with the value associated with that resource record set (e.g. IPv4 address for one of your resources).

If you are given a scenario where you need to set up Route 53 to provide the lowest latency possible for a user, what routing would you recommend?

Latency-Based Routing

What is Multivalue Answer Routing Policy in Route 53?

Lets you configure Amazon Route 53 to return multiple values, such as IP addresses for your web servers, in response to DNS queries. It is similar to Simple Routing in that you can specify multiple values for any record, but Multivalue Answer Routing also lets you check the health of each resource, so Route 53 only returns values for the healthy resources.