‫So now that we know what is a DNS,
‫let's have a look at Amazon Route 53.
‫So this is a highly available, scalable,
‫and fully managed and authoritative DNS.
‫What does authoritative means?
‫That means that the customer you can update the DNS records,
‫so you have full control over this DNS.
‫So the idea is that you have your clients
‫and they want to access your EC2 Instance @example.com
‫but right now your EC2 Instance only has a public IP.
‫Therefore what's going to happen
‫is that we're going to write some DNS records
‫into Amazon Route 53, into a hosted zone,
‫and when the client is asking for example.com,
‫then the Route 53 service will be able to say,
‫"Hey, you're looking for this IP 54.22.33.44,"
‫and then the clients will be able to connect directly
‫into our EC2 Instance.
‫So Route 53 is also a domain registrar,
‫so it will be able to register our own domain names there
‫such as example.com, and we'll be doing this
‫in the hands-on to allow us to get started
‫with this service.
‫So we have the ability to check also the health
‫of the resources within Route 53,
‫we'll see this in the section.
‫And this is the only service in AWS
‫that will provide 100% availability SLA.
‫Finally, why is it called Route 53?
‫Well, 53 is a reference to the traditional DNS port
‫used by DNS services, hence the name.
‫So in Route 53 you're going to define a bunch of DNS records
‫and the records define how you want to route traffic
‫to a specific domain.
‫So each record is going to contain a lot of information
‫such as the domain or the subdomain names
‫such as example.com.
‫The record type, and we'll see what types of record
‫we have available to us, for example it could be A or AAAA.
‫Then the value, so the value of the record,
‫for example, 12.34.56.78
‫The routing policy,
‫which is how a Route 53 will respond to queries.
‫The TTL, which is the amount of time
‫the record is going to be cached at the DNS resolvers,
‫also called time to live.
‫And then we have a lot of different supported
‫DNS report types in Route 53.
‫So we have, the ones you must know is A, quadruple A,
‫CNAME, and NS, so we'll have a look at those
‫in the hands-on.
‫And the advanced records that you can set,
‫but we don't need to know from an exam perspective,
‫are all the ones I just wrote right here.
‫So let's learn about the important record types
‫we need to know from an exam perspective.
‫So the A record is very simple,
‫it's to map a host name into an IPv4 IP.
‫So this is when you have, for example, example.com
‫that will be directed into 1.2.3.4.
‫Okay, great.
‫Then we have quadruple A.
‫So this is the same idea as A,
‫but this time we're going to match our host name
‫into an IPv6 address.
‫Then we have a CNAME, which is used to map a host name
‫into another host name.
‫And then the target host name of course may be an A
‫or a quadruple A record.
‫You can not create CNAMES in Route 53
‫for the top nodes of a DNS namespace or the Zone Apex,
‫and we'll see this in a future lecture as well
‫to understand how that works.
‫For example, you can not create a CNAME for example.com,
‫but you can create a CNAME record for www.example.com.
‫So we'll see how we can deal with this in a future lecture.
‫And then finally, NS is for name servers of the hosted zone.
‫They are the DNS names or IP addresses of the servers
‫that can respond to the DNS queries for your hosted zone,
‫and this will control how traffic is routed to a domain.
‫So let's have a look at what are hosted zones.
‫So hosted zones are a container of records,
‫and they will define how to route traffic
‫to a domain and its subdomain.
‫So we have two types of hosted zone,
‫we have the public of zones and the private hosted zones.
‫So whenever you buy a public domain name,
‫for example mypublicdomain.com, this is a public domain name
‫and therefore we can create a public hosted zone
‫and these public zone can answer the query,
‫"Hey, what's is the IP, underlying IP of the domain name
‫application1.mypublicdomainname.com?"
‫But we also have private hosted zones.
‫And these are for domain names that you,
‫they are not publicly available, they're privates,
‫and only you within your own virtual private cloud or VPC
‫can resolve this URL.
‫For example, application1.company.internal.
‫You may have seen this if you're working
‫for a private company, they sometimes have URLs
‫that you can only access from within your corporate network,
‫that's because this is a private URL, this is a private
‫and behind the scenes there is a private DNS record.
‫So for any hosted zones you're going to create an AWS
‫you're going to pay 50 cents per month,
‫so this is not free to use Route 53.
‫And if you are to register a domain name,
‫just like I will in the hands-on,
‫this will cost you a minimum of a $12 per year.
‫So just so you know, this section is not free.
‫So public versus private hosted zones, just to understand.
‫So public hosted zone can be answered,
‫can answer queries from public clients.
‫So when you web browser, for example, and say,
‫"Hey, give me example.com," and then it returns an IP.
‫And on the other end we have the private hosted zone.
‫So this is from within your VPC they live.
‫And so they allow you to identify private resources
‫with private domain names.
‫So for example, we have one EC2 Instance
‫that we want to identify with webapp.example.internal,
‫we have another EC2 Instance that we want to identify
‫with api.example.internal, and then we have a database
‫we want to identify with database.example.internal.
‫In which case we're going to register a private hosted zone,
‫and then in case the first EC2 Instance
‫is requesting for api.example.internal,
‫then the private hosted zone has an answer for it,
‫which is the private IP 10.0.0.10.
‫Then the EC2 Instance will connect
‫to the second EC2 Instance,
‫which may need to connect to database.
‫So it will say, "Hey, what's database.example.internal?"
‫And the private hosted zone will say,
‫"Well, this is this private IP."
‫And then the EC2 Instance can connect directly
‫into the database.
‫So the public hosted zone and the private hosted zone
‫work the exact same way, but just the public hosted zone
‫allows anyone from the internet to query your records,
‫so this is for your public records,
‫whereas a private hosted zone is only queried
‫from within your private resources, for example your VPC.
‫So that's it for the theory,
‫now let's go into the next lecture to register a domain
‫and then create some records.
‫So I will see you in the next lecture.