1. [SAA/DVA] What is a DNS?
Okay, so before we talk about route 53, we have to talk about what is a DNS. So this is a basic level lecture, but at least it will help you understand how DNS works. And this is something you’ve been using behind the scenes every day, but you don’t know about it exactly. So let’s have a look. So a DNS is a domain name system and what it will do is that it will translate human friendly host names into the targets server IP addresses.
For example, when you type in your web browser, Www. google. com, it will in the end give you back an IP address. And this is this IP address that your web browser will be able to access behind the scenes and get some data back from Google. So the DNS is the backbone of the internet. It is a way for you to understand how to translate these URLs, these host names into IPS.
So there is a hierarchical naming structure for DNS. And the idea is that at the root of Www. google. com, for example, there is the. com but then there is Example, which is a bit more precise than www. example. com or API example. So all of these are going to be the hierarchy of your domain names. Next we need to define a little bit of terminology regarding your DNS. So there is a domain registrar.
This is where you’re going to register your domain names and they could be Amazon, rooftop three, or it could be GoDaddy or any other domain registry you can find online. Then you have DNS records and they have different types and we’ll have a look at them in details in this section. So it could be a quadruple, a C name, NS, et cetera, et cetera.
Don’t worry, we’ll see those in details in this section, a zone file which contains all the DNS records. So this is how to match these host names to IPS or addresses name servers is servers that will actually resolve the DNS queries. And we’ll have a look at them as well in the section top level domains which is. com us in gov. org, et cetera, et cetera. Second level domain which is Amazon. com google. com. So you can see there are two words in between a dot and so if we take a look, for example at this FQDN, so fully qualified domain name, we have HttpApi www. example. com.
So the last dot at the end is called the root and it’s the root of all the domain names. Then the. com so. com is your TLD. So that’s your top level domain. The example is going to be your second level domain. Then we have www. example. com, that’s your subdomain. Then API. Www. example. com is your domain name. Okay, the http part of it is the protocol you want to use. And altogether we have the FQDN, which is the fully qualified domain name. So now that we know a little bit of terminology, let’s have a look at how DNS works. So we have a web server.
And let’s say, for example, that we have an IP. It’s a public IP, could be an easy to instance, for example, and the public IP is 910 1112, and we want to be able to access this using the example domain name. So we’re going to register this example domain name on one of our servers for the DNS. But let’s see how the computer, your web browser can access it and can get that response. So your web browser is going to want to access example, and to do so, it’s going to ask its local DNS server, hey, do you know what Example is?
Now this local DNS server is usually assigned and managed by your company or assigned by your Internet service provider dynamically. And if the local DNS server has never seen this query before, what it’s going to do is first ask the root DNS server managed by the Icin, the ECan organization, and it’s going to say, hey, do you know what’s example, which is the first server that’s going to be asked? And the root DNS server is going to say, I’ve never seen it, but I know so. com is NS. So it’s an NS record name server. And go see 1234, this public IP. So this is saying to local DNS, hey, I don’t have this answer, but I’m getting you a little bit closer to the answer because I know the. com domain and the domain name server has this IP 1234. So the local DNS server saying, okay, good, now I’m going to ask the top level domain. So the. com domain server at 1234, I’m going to ask for the answer of my query.
So this is another domain managed by Iana the Ina, and the example is going to be asked again to this DNS server. So do you know about example? And the DNS server is going to say, hey, I don’t know about example. I do know about example. I don’t have the answer to your query right away, I don’t know which record it is. But there is a server called example that I know about, which is at 5. 6. 7 . 8. That’s the public IP that you should ask the answer to my question, to your question. So the DNS server is then going to go to our final server, which is the sub level domain DNS server. And this is a server that is going to be managed by your domain registrar. So it could be, for example, Amazon Route 23 and so on. So the DNS server is going to say, hey, do you know about example? And the DNS server will have an entry, for example, come. And so it will say, hey, yes, of course I know example.
And it turns out that example, I know that it’s an A record and that the result of it isn’t the IP 910 1112. So the DNS server now knows the answer by recursively asking DNS servers and finding the most specific one. And then it says, okay, hey, yes, I’m going to cache that answer right away because I want to be able to if someone is asking me again, for example, come, I want to get it right away, give them the answer. So it’s going to send back the answer into your web browser and your browser that has the answer. And using this IP address, then it’s going to be able to access your web server.
So this is how DNS works. So you’ve been using DNS behind the scenes all along, all your life. For example, when you access Www. google. com, you’re using DNS or any website. But now we see how the DNS queries work. So this is just some background knowledge because now we’re going to go into Route 53 and learn how to manage a DNS server on our own. So I hope you liked it, and I will see you in the next lecture.
2. [SAA/DVA] Route 53 Overview
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 Et Two instance@example. com. But right now your Et Two 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 comm, then the Route 53 service will be able to say, hey, you’re looking for this IP 54 22 dot 33 34 and then the clients will be able to connect directly into our 82 instance.
So Route 53 is also a domain registrar, so we’ll be able to register our own domain names there such as Example Come. 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 fla. 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, example, the record type and we’ll see what types of record we have available to us. For example could be A or AAA, then the value.
So the value of the record, for example, one 2345-678-9123, the routing policies, which is how 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.
Okay, so let’s learn about the important record types we need to know from an exam perspective. So the error record is very simple. It’s to map a hostname into an IPV four IP. So this is when you have for example, example that will be directed into 1234. Okay, great. Then we have quadruple a So this is the same idea as A. But this time we’re going to match a hostname into an IPV six 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 cannot create C names in route 53 for the top nodes of a DNS namespace for this on Apex. And we’ll see this in the in the future lecture as well to understand how that works. For example, you cannot create a CNAME for example, but you can create a CNAME record for www. example. com. So we’ll see how we can deal with this in future lecture. And then finally, NS is for name servers of the hosted zone. They are the DNS names or IP addresses of these servers that can respond to the DNS queries for your hosted zone. Okay? And this will control how traffic is routed to a domain. So let’s have a look at what are hosted zones. So hosted zone 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 hosted zones and the private hosted zones. So whenever you buy a public domain name, for example, mypublic domain. com, this is a public domain name, and therefore we can create a public hosted zone. And this public hosted zone can answer the query, hey, what is the underlying IP of the domain name? Application one, mypublic domain name. But we also have private hosted zones. And these are for domain names that are not publicly available. They’re private and only you within your own virtual private cloud. So VPC can resolve this URL. For example, application one 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 zone you’re going to create in AWS, you’re going to pay fifty 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 $12 per year. So just so you know, this section is not free. Okay? So public versus private hosted zones, just so you understand. So public hosted zone can be answered, can answer queries from public clients. So any web browser, for example, say, hey, give me example, 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 EC two instance that we want to identify with webapp example internal, we have another EC two 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 EC two instance is requesting for API example internal, then the private hosted zone has an answer for it, which is the private IP ten 00:10.
Then the instance will connect to the second ISTEW instance, which may need to connect to the 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 east two instance can connect directly into the database. So the public hosted zone and the private hosted zone works 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 the private hosted zone is only queried from within your private resources, for example, your VPC. Okay, 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.
