Okay.
Hello loggers and welcome to this lecture.
Congratulations you're at the very end of the DNS section.
I know DNS is not the most exciting topic in the world but you do definitely need to know it to be a
solutions architect in real life.
So you will definitely get Route 53 questions on your exams.
It's probably going to be worth around four to five marks to make sure you do understand it inside out
going into your exam.
So let's cover off what we've learned.
My route 53 exam tips.
Now always remember that Elastic Load balances do not have predefined IP for addresses you resolve to
them using a DNS name.
I appreciate we haven't covered offer Elastic Load balance as much yet in the course we will get that
when we move on to the highly available section of the course and E.L. bays or El Baz Albee's whatever
it is you want to call them.
They are extremely important topic for the certified Solutions Architect associate exam.
You should definitely understand the difference between an alias record and a C name.
If you just remember that yellow pages picture that we had up so we had all our records which was just
people's names and then their telephone numbers and a C name was that Bruce Wayne or I think it was
Batman and then it said see Bruce Wayne.
So that's exactly how a C name works.
And then given the choice between an alias record on a C name in an exam scenario I would always choose
alias most of the time Amazon are gonna be asking things like your naked domain name you need to map
your naked domain name or your zone Apex record to an S3 bucket what should you be using a C name or
an alias record where you want to be using an alias record we're gonna see how to do that in the service
section of the course.
So some common DNS types have got our start of authority record our NHS records our records our sea
names our AirMax records and LPT our records and the following routing policies are available with Route
53 so we started off with simple rooting we then looked at weighted rooting latency base rooting fail
over rooting geo location rooting geo proximity rooting but we had to do that using the traffic flow
and then multi value and rooting.
We also learned all about health checks.
You can set health checks on individual records sets if a records set fails a health check it's going
to be removed from Route 53 until it passes the health check again and you can set up S.A. notifications
to alert you if a health check has failed.
So simple rooting if you choose simple reading policy you can only have one record with multiple IP
addresses and you can't have any health checks if you specify multiple values in a records set route
53 will return of the values to the users in a random order.
So here's our user typing in a DNS address.
Route 53 is giving them the first record and then it's giving them the second record but we can't have
a health check on that one waited rooting policies we've got our user typing in a DNS address and we're
setting weights so we're sending 20 percent of the traffic to USD 1 and 80 percent of the traffic to
us W1.
So that's how it weighted.
Routine traffic works latency base rules rooting is based on our users location and the latency.
So our South African user is going to visit our website.
It's behind Route 53 and essentially they're going to get 50 more 54 milliseconds.
If they use us W to 300 milliseconds.
If they use AP se too so of course Route 53 is gonna send them to the fastest fleet of easy two instances
first which is gonna be EU W to fail over rooting.
This is where we start using our health checks.
So essentially we've got an active passive environment our active environment could be us W2 and our
passive environment could be AP se too if for some reason our easy to instances or a region goes down
it's gonna detect this using a health check and it's gonna fail over to our passive environment geo
location rooting allows our European customers to be sent to our European servers and it allows our
US customers to be sent to our US servers.
It doesn't have anything to do about latency it actually physically knows where our customers are and
then it makes routing decisions based on that that we configure.
So that's how geo location rooting works.
Sheer proximity rooting as you saw we could start going down the rabbit hole.
This is an advanced networking specialty topic.
It is not something that comes up in the solutions architect associate exam or even in the professional
exam but it allows you to create you know route traffic to your resources based on the geographical
location of your users as well as your resources and to use geo proximity routine.
You must be using Route 53 traffic flow and then finally we had our multi value answer policies and
essentially this is the same as simple base rooting except you get health checks and so you can have
multiple values within your records sets.
So we've got our records set in here and we've got our first and our second.
And if one fails a health check what's going gonna happen what's going to remove that from the record
set or it's gonna stop serving that record until it passes the health check so that is it for this section
of the course.
You've done very very well.
The next section we're going to learn all about the species and that is crucial to passing your certified
Solutions Architect associate exam.
And it is actually an awful lot of fun.
So if you got the time please join me in the next lecture.
Thank you.