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So now that we know what is a DNS,

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let's have a look at Amazon Route 53.

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So this is a highly available, scalable,

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and fully managed and authoritative DNS.

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What does authoritative means?

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That means that the customer you can update the DNS records,

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so you have full control over this DNS.

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So the idea is that you have your clients

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and they want to access your EC2 Instance @example.com

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but right now your EC2 Instance only has a public IP.

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Therefore what's going to happen

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is that we're going to write some DNS records

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into Amazon Route 53, into a hosted zone,

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and when the client is asking for example.com,

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then the Route 53 service will be able to say,

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"Hey, you're looking for this IP 54.22.33.44,"

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and then the clients will be able to connect directly

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into our EC2 Instance.

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So Route 53 is also a domain registrar,

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so it will be able to register our own domain names there

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such as example.com, and we'll be doing this

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in the hands-on to allow us to get started

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with this service.

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So we have the ability to check also the health

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of the resources within Route 53,

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we'll see this in the section.

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And this is the only service in AWS

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that will provide 100% availability SLA.

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Finally, why is it called Route 53?

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Well, 53 is a reference to the traditional DNS port

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used by DNS services, hence the name.

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So in Route 53 you're going to define a bunch of DNS records

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and the records define how you want to route traffic

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to a specific domain.

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So each record is going to contain a lot of information

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such as the domain or the subdomain names

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such as example.com.

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The record type, and we'll see what types of record

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we have available to us, for example it could be A or AAAA.

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Then the value, so the value of the record,

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for example, 12.34.56.78

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The routing policy,

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which is how a Route 53 will respond to queries.

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The TTL, which is the amount of time

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the record is going to be cached at the DNS resolvers,

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also called time to live.

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And then we have a lot of different supported

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DNS report types in Route 53.

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So we have, the ones you must know is A, quadruple A,

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CNAME, and NS, so we'll have a look at those

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in the hands-on.

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And the advanced records that you can set,

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but we don't need to know from an exam perspective,

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are all the ones I just wrote right here.

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So let's learn about the important record types

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we need to know from an exam perspective.

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So the A record is very simple,

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it's to map a host name into an IPv4 IP.

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So this is when you have, for example, example.com

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that will be directed into 1.2.3.4.

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Okay, great.

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Then we have quadruple A.

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So this is the same idea as A,

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but this time we're going to match our host name

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into an IPv6 address.

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Then we have a CNAME, which is used to map a host name

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into another host name.

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And then the target host name of course may be an A

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or a quadruple A record.

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You can not create CNAMES in Route 53

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for the top nodes of a DNS namespace or the Zone Apex,

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and we'll see this in a future lecture as well

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to understand how that works.

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For example, you can not create a CNAME for example.com,

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but you can create a CNAME record for www.example.com.

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So we'll see how we can deal with this in a future lecture.

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And then finally, NS is for name servers of the hosted zone.

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They are the DNS names or IP addresses of the servers

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that can respond to the DNS queries for your hosted zone,

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and this will control how traffic is routed to a domain.

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So let's have a look at what are hosted zones.

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So hosted zones are a container of records,

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and they will define how to route traffic

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to a domain and its subdomain.

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So we have two types of hosted zone,

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we have the public of zones and the private hosted zones.

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So whenever you buy a public domain name,

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for example mypublicdomain.com, this is a public domain name

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and therefore we can create a public hosted zone

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and these public zone can answer the query,

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"Hey, what's is the IP, underlying IP of the domain name

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application1.mypublicdomainname.com?"

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But we also have private hosted zones.

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And these are for domain names that you,

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they are not publicly available, they're privates,

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and only you within your own virtual private cloud or VPC

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can resolve this URL.

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For example, application1.company.internal.

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You may have seen this if you're working

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for a private company, they sometimes have URLs

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that you can only access from within your corporate network,

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that's because this is a private URL, this is a private

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and behind the scenes there is a private DNS record.

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So for any hosted zones you're going to create an AWS

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you're going to pay 50 cents per month,

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so this is not free to use Route 53.

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And if you are to register a domain name,

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just like I will in the hands-on,

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this will cost you a minimum of a $12 per year.

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So just so you know, this section is not free.

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So public versus private hosted zones, just to understand.

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So public hosted zone can be answered,

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can answer queries from public clients.

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So when you web browser, for example, and say,

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"Hey, give me example.com," and then it returns an IP.

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And on the other end we have the private hosted zone.

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So this is from within your VPC they live.

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And so they allow you to identify private resources

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with private domain names.

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So for example, we have one EC2 Instance

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that we want to identify with webapp.example.internal,

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we have another EC2 Instance that we want to identify

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with api.example.internal, and then we have a database

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we want to identify with database.example.internal.

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In which case we're going to register a private hosted zone,

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and then in case the first EC2 Instance

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is requesting for api.example.internal,

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then the private hosted zone has an answer for it,

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which is the private IP 10.0.0.10.

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Then the EC2 Instance will connect

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to the second EC2 Instance,

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which may need to connect to database.

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So it will say, "Hey, what's database.example.internal?"

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And the private hosted zone will say,

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"Well, this is this private IP."

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And then the EC2 Instance can connect directly

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into the database.

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So the public hosted zone and the private hosted zone

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work the exact same way, but just the public hosted zone

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allows anyone from the internet to query your records,

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so this is for your public records,

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whereas a private hosted zone is only queried

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from within your private resources, for example your VPC.

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So that's it for the theory,

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now let's go into the next lecture to register a domain

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and then create some records.

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So I will see you in the next lecture.