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Understanding Core AWS Services

28. Connecting to RDS via CLI

Hey everyone, and welcome back. Now present and in the previous video we had concluded after our database was in thst age. tion stage. So now if you loo information section, fo section, the creation has into the available category, o ava within thed witpoint,e end point you now ha point through oint through which we can conn database. e database. So video, day's video we will how we into how we can connect to our daCL I. se via CLI. Now, the very first thing that y make sure ofto make sure is that the connectivity between your your RDS and your RDS is estab and it perfectly. perfectly. Now, one of twayseto check way to check that is thro command. NC command verify theater’s verify NC is present and NC is not present here. So let's do a quick review of what NC provides on NC.And we'll have to install a package called Nmapat. Perfect. So basically, this is my test EC two instances. You can run these commas in any EC2 instance that you might have for your own testing.

So I'll do an NC ZB, I'll pay the hostname or the URL, and I'll specify the port 3306. And basically now you see it says connected. That means the connection is working perfectly. So once the connection is working perfectly, the next thing that we need to do is connect to the database. Now, remember that SSH to this will not work because RDS does not allow SSH, primarily because it is a managed service. So you will not be able to SSH into your RDS instance. So the only thing that you will be able to do is connect via the MySQL client to your RDS database. So if I type MySQL again, MySQL is not found. So we can go ahead and do a YamWatt, and I'll do a MySQL. It will give me the package name where MySQL binary is available. I'll say YamYard install; I'll say MariaDB. So whenever you are using Ubuntu, you typically have a package called MySQLclient; unfortunately, on Amazon Linux, that package is not available directly. So you'll have to do the YMP installation of MariaDB completely. Perfect.

So our package is now installed. So if you just type MySQL, it actually works. It gives you an error because we have not really specified anything yet. Perfect. So the command is that you have to do MySQL hedge, which basically means the hosting, and you will have to put the end point, which you see over here. I'll press it here, and then you have to specify the username. If you remember the user that we had created, the name was KP admin and Hyphen p.

When you do hyphen p, it will ask you for the password in the interactive prompt. And once you do it, you see that it has automatically logged in. So if you do a "show databases," it will basically give you a list of all the databases that are present. Now, during the creation time, we created a database called Kpops, and hence our Kpops database is present over here. So this is how you can connect to your RDS with the help of the MySQL client. Now, in case you are not able to connect, make sure that the security group that you have associated with RDS allows appropriate inbound details. So in my case, if you see that port 3306 is allowed from a specific IP, and this is basically my IP from the ISP that has been assigned to me, So that's about it for the basics of how you can connect to RDS via CLI. I hope this video has been informative for you, and I look forward to seeing your next video.

29. Understanding NoSQL Databases

Hey everyone, and welcome back. So today we'll be speaking about the basics of a NoSQL database. Now, in the previous lectures, we laid a good foundation for relational databases and the features and functionality that they provide. So that will provide us a good foundation to understand the NoSQL-based database types. So let's go ahead and understand what this basically means. So in definitive terms, a NoSQL database is also referred to as a nonrelational database or a NonSQL database. And it provides a means of storage and retrieval of data that is modelled by means other than tableau representation using a relational database. So this is a very simple understanding of what a "no sequel database" really means. So when we speak about a relational database, it is structured in a tabular form. So you have one table, and inside the table you have three columns over here.

So this is what it means that the relational database was based on the tabular representation. However, nonrelational is not really based on this kind of structure. So the second point is that NoSQL has gained huge popularity because they are simpler to use, flexible, and can achieve performance that is very difficult with the help of traditional relational databases. Now, we will be speaking about this in the relevant section whenever it is necessary. But when you compare a relational database and a NoSQL database, the representation would look something like this: So in the relational database, again, you have columns. However, when you consider a no-SQL database, a specific type of no-SQL database works based on the key value stored.

So you have a key over here, which is eight, and the value is 26. So again, you have a key as an interest. Value is astronomical, key is name, and value is hers. So this is what is called a "key value store." You don't really have a predefined structure like name, age, or interest. So that predefined structure is not present. We will be discussing this in the later part of this chapter. But before that, let's look into the advantages of a NoSQL database before we jump into the practical. So there are a lot of advantages to an SQL database over a standard relational database.

One is that it is schema-free. The second is horizontal scaling. It can really scale horizontally, and this is one of the advantages of having a NoSQL data vision. The third is easy replication. And fourth, it can manage huge amounts of data. The last thing that we have to remember is the format. There are various formats that the sequel database does not support. First is the document database. The second is the graph store. Third are key value pairs. This is something that we were discussing in the last lecture. So you have a key value pair over here, and the last is white-column stores.

So for the time being, we just remember this, and whenever it is necessary for us to talk about each of these in detail, we will be speaking. However, for timing purposes, we will be primarily focusing on the key value store. So let's do one thing. Let me show you one of the NoSQL-based implementations of Amazon, which is DynamoDB. And we'll be focusing on the first point, which is schema-free. And we'll understand exactly what "schema-free" basically means. So I have a DynamoDB over here. So DynamoDB is basically a non-relational database. So if you see it's a no relational database, here I have created a table called Test.

So if you will see over here, I have a few columns or a few items present over here. So what "schema-free" basically means is that I don't really have to specify beforehand what a schema would really look like and what the column is. So here you have a name column, an age column, and an interest column. So again, if for one user I want to have one more column, let's say "college," and I don't want to have that column for the second user with a Z, then in a relational database I would have to put a null value over there. However, if there is no sequel, we don't really have to do that. Let me show you. Let's assume I want to put a column for the first item over here or in the first row.

And for the second row, I really don't want to put any colleges. So in this case, I have two rows. I'll open this up, and here you see we have a key-value-based store. You don't really have any columns or rows that are present. So let's do one thing. What I'll do is click on Insert, insert a string, and name it "college." Let me put it as "spitting," okay?" And I'll click on "Save." So now what you are seeing is college value over here. But in this second item, the college value is not there at all. So here you will see that it is showing the college. Now, the reason it is showing college is because it is easier to view. But when I open up the second item, there is no college field at all. So this is what is called a schema-free database. You don't really have to specify a specific schema beforehand for the NoSQL databases.

So this provides a great advantage for the data, which is unstructured. Unstructured means you don't really have a specific structure for the database. When you talk about a relational database, you need to have a specific structure. Like the data, it should have a name, an age, and an interest. So this structure should be defined ideally beforehand only. Now, in cases where there is a clearly defined structure, you can use an Oracle database because it provides great flexibility. And this is what is called a "schema freebies" implementation. Now, there are again a lot of advantages that no sequel database would provide. We will be speaking about this in the relevant lectures. But for the time being, I hope you understand what a schema-free database would really look like and what a key value SO would really look like. So in the next lecture, we'll go ahead and understand what DynamoDB is and explore a lot of its other features.

30. Understanding CloudWatch

Hey everyone, and welcome back. In today's video, we will be discussing the AWS Cloud Watch service. Now, Cloud Watch is basically a monitoring service that can monitor your servers as well as your applications. Now, a Cloud Watch can do much more than a traditional monitoring system based on a matrix. It can even collect and monitor log files, which can be your system or your application log files. So the below screenshots can help you better understand where, on the left hand side, you have various data points related to the CPU utilisation of your EC2 instances.

So all of these basically come from Cloud Watch. Now, once you record the CPU utilization, you can even set alarms based on that. So let's say that when CPU utilization is greater than 70%, then you should get an alarm on your email or on your SMS saying that this EC Two instance has a CPU utilization greater than 70%. So all of those functionalities can be achieved with the help of Cloud Watch. So before we discuss more, let's go ahead and understand this from a practical aspect. Now, in the EC-2 console, I am on my demo-server one server. I have selected the server that is running, and if I go to monitoring, you will see that there are a lot of Cloud Watch metrics that are available. So these Cloud Watch metrics are for CPU utilization. You have the disc-related metrics. If you go down, you have metrics related to network as well as status along with CPU credit usage.

So all of these are basically matrixes that are coming from Cloud Watch. Now, if you click over here, you can actually see that at this specific point, the CPU utilisation was 40%. It is also showing you the time, which is Thursday, November 29, 2018 at UT. So it is also showing you the time frame over here. Now, you can even set the time range to the last 24 hours or even the last two weeks if you intend to do so now. The period is five minutes. So it will basically record the events here every five minutes. Now, this is one of the features of Cloud Watch. Basically, if you go to the Cloud Watch console, let's go to the Cloud Watch console. And this is basically the Cloud Watch console. This is a new GUI that AWS has recently launched. If you are aware, AWS keeps changing its graphical user interface, and it really becomes challenging sometimes challenging. Specifically, when you're recording the video and they change the GUI after a few months, you have to rerecord many times anyway. So, coming back to the topic, this is a Cloud Watch console.

Now, we have already discussed that CloudWatch does more than just monitoring. It can also do various things like alarm. It can also monitor log files. So if you look into the alarms over here, there are a lot of alarms that have been traced. So these are related to the blog and some websites that I run for certain clients. So these are all the alarms that are set. So for this alarm, if you see that the CPU utilisation is greater than or equal to 80%, then I should get an alarm. So all of these are part of the alarm functionality. Now, one more interesting part that you typically see are the logs. Logs are basically where you can store your system or even your application logs within Cloud Watch.

So typically, let's take an example. So let's go to Flow Logs over here, and I'll click on a random interface, and basically, you can see that these are all the log files that are being stored within the Cloud Watch. Something similar to -- you can say Kabana; if you have heard about Elk Stack or various others, it can be Splunk; but definitely, it's not like Splunk at all. It just provides you with very basic features related to pushing your logs to Cloud Watch logs. Along with that, there are certain new things, like Cloud Watch logins, one of the new services that AWS just released last week. And the matrix is something that we have already seen. Now, we had seen the matrix of EC 2. Now do remember that for your EC two instances, there can be a lot of matrix that can be available. So all of these, if you see them, are all the matrix.

Now, Cloud Watch does provide a matrix not only for ECTwo instances but for various other services as well. And you will be able to see these services within this specific list. So you have DynamoDB, you have RTS, you have ELPS Three, et cetera. Let's take one more example of an RDS database. So let's go to RDS. And if you go to DB instances, I have one called Kplatz. I have one DB. Let's click on that. And if you go to monitoring now, you'll see the matrix, which is associated with the database instance. So here you have a matrix like CPU utilization, DB connections, free storage, free memory, the right IOPS, read IOPS, and if you go to the next screen, you also have binary logging, disc usage, queue depth, and various others. So all of these matrices come pre-built with Cloud Watch. Definitely. You can even create your own matrix if you need to. Cloud Watch does provide that flexibility.

31. Understanding Simple Notification Service

Hey everyone, and welcome back. So today we will be speaking about a very interesting topic that I am sure most of you will like, which is called the social networking site. So let's go ahead and understand the basics of what SNS is all about. SNS stands for Simple Notification Service, and SNS is a fully managed messaging and mobile notification service for delivering messages to the subscribed endpoints. Now, the concept is very similar to what we had been discussing in the SQS as well, where you have a publisher on the left hand side and on the right hand side you have consumers, and this is the SNS topic.

So what happens is the publisher will send a message to the SNS topic, and the SNS topic will forward that message to the number of subscribers who are subscribed to this specific topic. Now, there can be various kinds of subscribers that can be connected. You have HTTP, you have Lambda, you have mobile, which can be push notifications, SMS, you have email, and many others. So let's do one thing: let's look into the practical session so that this concept becomes much more clear for us. So, I have a SNS topic that was created. Let me show you.

This is the SNS dashboard, and under this there is a SNS topic. So when I click on the ARN, this is the SNS topic. If you look into the protocol, I have three configured endpoints, which are email, SQS, and SMS. So what I have right now are three configured endpoints over here that subscribe to this SMS topic. One is email, one is SMS, and one is SQS. So let's do one thing. Let me click on "Publish to Topic." I'll click here, and it is asking for a subject. The subject would be "test," and I'd say this is our first SNS topic, and I'd click on "Publish message." Now, if you might have heard, I got a notification on my phone.

Let me show you. I'll open this up. We'll start with SMS first, and let me just quickly open If you see over here, and I am not sure if you're able to see it, it says that this is our first SNS topic. If you're able to see, let me just put in more detail, and this is basically what it's all about. So this is all about the SMS part. We have three subscribed endpoints: one is SQS and one is email. So let's do one thing; let me go to SQS. Let's click on View and start pulling messages.

So we'll start with the most recent one. So this is the recent one, and I'll click on more details, and you'll see this is our first SNS topic. So this is the second one, and the third one goes to the email. And in the email, the subject would be the message subject that you had typed, and the content would be that this is a first SNS topic. So what really happens is that you create a topic in SNS. So this becomes a topic, and whatever messages a publisher sends to this specific topic, the topic will forward the message to all the subscribed endpoints for this specific SNS topic.

Now, there are various endpoints that you can subscribe to. Let me show you. When you click on "Create Subscription," you have a protocol of "https://" and "email:" SQS. You have application lambda and SMS. So you'll have to remember the protocols that are used or supported by the SMS. Now, it also supports push notifications. And this is quite interesting because, if you are not aware of what a push notification is, I'm sure most of you have gone through one. So in your mobile, you might have seen that you get these kinds of messages every now and then.

So these are called "push notifications," and you can send push notifications with the help of SNS as well. Now, this is it for this lecture. In one of the organisations that I have been working with, what we actually decided was that whenever there is an alert email, it should automatically go to WhatsApp. Because most people do not check email regularly, they do check WhatsApp. So quite an evil plan was being executed. Anyway, so this is it. In this lecture, I just wanted to show you a demo on what SNS is all about.

32. Introduction to DNS

Hey everyone, and welcome back. So today we will be speaking about a very important topic called domain name systems. Now, the domain name system is considered one of the backbones of the internet. And I am pretty sure that many of you have heard about DNS as a term in many instances. So the reason why it is considered one of the backbones of the internet is the same reason why there are a lot of major attacks that happen on the DNS in order to slow down the overall internet speed. So if you'll see in the first article, the biggest DDoS attack in history slows The Internet breaks a record of 300 GB/s. That's quite huge.

And on the other aspect as well, a lot of hackers or attackers try to attack the DNS servers so that things go a bit slowly, and we'll understand why, what the importance of DNS is, and how an attack on DNS can slow down the entire process. So let's understand with a simple example. So in a phone, specifically when you store an integer, there are two important aspects that happen.

First, you have to store a name; that is the first aspect. And second, you have to store an associated number. So you have Mr. A, and there is an associated number with Mr. A. Second, you have Mr. B, and you have his associated number; you have Mr. C, and you have his associated number. So whenever you want to call someone, what you do is go to the contact list and click on a specific contact, and it will automatically start calling.

So you don't really have to remember every person's number. So generally, whenever you get a SIM card, you get an associated number. But it is not really as far as humans are concerned; remembering numbers is not a very ideal way. We remember names much more quickly. And this is the reason why. What happens in a phone book application is that there is a mapping between a name and a number? So humans remember the name, and computers, as they're good with numbers, store the number, and the phone book application does a mapping between a name and a number. I hope you understand the basic concept of how the phone book application really works.

So in a similar way, DNS also works. So if you talk about the internet or servers, everything is based on numeric systems. So every server has a specific IP address. So you have an IP address for the Google.com server and a different IP address for the Yahoo.com server. Similar to how a phone number works, every person has a different phone number.

You cannot have the same number for two different people. Similarly, every website or every networking device on the internet has a unique IP address. So Google.com might have this IP address; Facebook might have this IP address at yahoo.com; and Microsoft might have this specific IP address. And since humans are not very good at remembering these IP addresses, What happened was that there was a need for a mapping between a name and the IP addresses. And the software that does this specific mapping between name and IP address is called the DNS.

So what really happens is that DNS servers are responsible for translating or converting a domain name to an IP address. So you supply the domain name to the DNS server, and the DNS server will respond to you with the corresponding IP address associated with the domain name. So let's do one thing. Let's go ahead and try this out and look into how this would really work.

So let me just show you. I'll be promoting my website. By the way, This would be a blog. So I have a blog called Zealbora.com. Now, again, since we are not putting in an IP address, I don't really remember the IP addresses, right? That's why DNS was introduced. So I'll press Enter, and now what you will see is that the entire website is getting loaded, or I would say the entire blog got loaded. Now, in the back end, there are a lot of things that have happened, and everything begins with a DNS.

Because unless and until you get the IP address associated with Zilbora.com, you really cannot do anything. So let's do one thing. Let's run an NSlookup on Zealbora.com and press entertainment. What exactly is happening over here? It gave us a corresponding IP address associated with the domain Zealbora.com. And this is exactly the first process that happens. Now, this entire process is based on a request and response where my client, which is Nslookup, sent a request to the DNS server asking for the IP address associated with Zilbora.com. And the DNS server gave the response of the IP address that is associated with the domain name—very similar to a phone book application, right? You click on a contact list, and it will give you a phone number very similar to that. So this is the basic about how it really works or how DNS really is.

In the next lecture, we'll actually look into what happened behind the scenes as far as packet capture is concerned when we ran an Lookup command. So this is it. Most applications that deal with domain names have the capability to resolve the corresponding IP address. So if you even do a ping on Zillbora.com, ping will actually resolve the IP address associated with Zealbora.com, and it will do a ping on the IP address.

So if you'll see over here, if I do aping on Zilbora.com, what really happened was that it resolved the IP address associated with the domain name, and then once it resolved the IP address, it is actually sending a request for a specific IP address itself. So this is it. In this lecture, I hope you understood the basics of what the DNS is all about. We'll be studying in depth how DNS really works behind the scenes. So this is it. About this lecture: I hope this has been informative for you, and I look forward to seeing you in the next lecture.

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