Hi, everyone, and welcome back.
Now, in today's video, we are going to discuss about the basics of Route 53 resolver.
Now, at a very high level overview, a Route 53 resolver responds to the dense queries from the resources
for various type of records like public records, VPC, specific DNS, as well as the private hosted
zones.
And this resolver is available by default in all the VPC.
So let's go ahead and understand this with a small animation where you have a certain set of easy two
instances that are part of a VPC, and you also have a Route 53 resolver.
Now these set of instances, whenever they make a query, the Route 53 resolver takes care of the overall
resolution and it will respond back with the appropriate DNS answer.
However, one thing to note is that it is not necessary that you make use of a Route 53 resolver.
You can also have your own custom DNS server where you can go ahead and send the query and the responses
can be given to you.
However, the route 53 resolver is something that is default and makes things much more simpler.
Now when we discuss about Route 53 resolver, it is important to know the overall address.
And the address is VPC plus two IP address.
For example, if the VPC CIDR block is one 7230 100 16, then the resolver IP would be one 7231 0.2,
which is VPC plus two IP address over here.
Now whenever you launch an ec2 instance by default in the result corner of this VPC plus two IP addresses
already configured.
So you don't really have to worry about the name resolution.
For example, whenever you look into the contents of the ETSI result conf in the EC two instance, you
will generally see the line of name server followed by the IP address like one 7231 0.2.
Again, note that depending upon the VPC CIDR block, this name server value will also change.
So let's do one thing.
Let's go ahead and look into this practically Now for today's video, I have an easy two instance running
in a default VPC with a CIDR of one 7231.
So let's go ahead and quickly connect to this instance.
So let me quickly add the IP address.
Now, within this instance, if you look into the ETSI result conf file.
You see that the name server is one 7230 102 So any time when you make a query, for example, when
you require DNS resolution, the request always goes to the specific name server, which is nothing
but the Route 53 resolver.
Now, to make things clear, let's also launch one more instance in a different VPC.
So I'll say new VPC EC two.
I have multiple VPC in this region just for demo.
So let's do one thing.
Let's launch it in a VPC with a CIDR of 1070 700 16.
I'll go ahead and quickly launch the instance.
Let's go back to the instances.
So our current EC two instance is running.
Now let's copy the public IPV four of this EC to and from a terminal.
Let's log out from the previous EC two instance.
And let's quickly connect to the newer easy to.
Great.
Now, if you look into the results of this SC to.
This time you see, the name server has changed to 1077 0.2, which is the VPC plus two IP address.
All right.
So I hope with this you understood the basics on how Root 53 resolver takes care of the overall DNS
resolution by default.
And this in turn makes things much more simpler.
Now, when we discuss about the overall query resolution, note that Route 53 resolver automatically
answers the DNS queries for first, the local VPC domain names for easy two instances.
For example, you have EC two hyphen IP address, dot compute one dot Amazon dot com.
So whenever a query is made, the resolver automatically responds.
Your second is it also responds to the records that are in the private hosted zone.
This is something that we'll see in just a moment.
And third is it also resolves for the public domain names and if required, it can also perform the
recursive lookups.
So let's also quickly look into this.
Now, the first point that we were discussing is the local VPC domain name for EC, two instances.
So if you'll see you have the public IPV four DNS, So this type of address can be automatically resolved.
Then you have the records in a private hosted zone.
This is also something that is important.
For example, I have a private hosted zone call example DOT internal and within here I have a record
college demo, dot, example, dot internal.
So this type of record can also be resolved by the Route 53 resolver.
For example, if I quickly do this lookup on demo dot example, dot internal, you see we are getting
the response back.
Now note that this domain example dot internal is not a public domain.
For example from my local workstation, if I do a lookup on demo dot example, dot internal, you immediately
get a response back stating non existent domain.
So whatever records that we have in this example dot internal or private as you can see over here,
and this can only be resolved from resources like EC two instances similar to what we have seen here.
All right.
So I hope with this you also understood the second point where records in private hosted zones can also
be resolved by the Route 53 resolver, and the third is related to the public domain name.
This is already something that we know where if you try to resolve public domain like Google, Yahoo,
etc. Route 53 resolver can resolve the overall record.
Great.
So that's a very high level overview about the Route 53 resolver, and with this will conclude today's
video.