Amazon Cloud Support Associate Interview Questions

basics Linux fundamentals
like system calls , strace , linux mange memory, shared memory, kernel using, boot process, DNS resolving ( how to resolve name to IP or what happen when you vist amazon.com), basics commands  

network basics like TCP/IP model, tcpdump, tcp 3 ways hand check, ping ,telnet, , network basics like TCP/IP model tcpdump tcp 3 ways hand check ping telnet and most network fundamentals  


what do you know about AWS tools? do you use it?
draw structure for simple website ?  



Windows Booting Process? Linux booting Process?
Windows BSOD error troubleshooting?
Moderate level Pattern printing coding question.
DNS? Subnet qs with numerical type ? DHCP? Routers?Switches?Gateways?
Virtual Memory?Thrashing?

Networking, troubleshooting, operating system  

main questions on linux and networking  

LINUX commands and have a brief knowledge of all OSI layers.  
Linux : how to kill a process , what does ls -la do
windows : what does task manager do and whats on it
TCP VS UDP
OSI model
Tell me about AWS what do you know
Behavior : have you ever had a problem and how did you solve it  


1. What command checks for running processes?
2. What is TCP and UDP?
3. You said that in TCP, connection is established, how is this done?
4. What command shows the hops between two networks?
5. How does traceroute command obtain these hops?
6. What is MTU?
7. What command checks for open ports?
8. What does the inode command do?
9. How do you edit the file descriptor?
10. How do you open files of a specific process?
11. What command checks the routing table in Linux?
12. Which directory are log files stored?
13. Which directory are third party software stored?
14. What is DNS?
15. Tell me about the DNS process. (The entire technical process)
16. What is DHCP.
17. Tell me about the DHCP process. (The entire technical process)
18. Tell me examples of TCP.
19. Tell me examples of UDP.
20. What command checks port connection?








Virtual memory  

How ip address are allocated  

Difference between tcp and udp  

Osi layers  

What is virtual memory?
Difference between process and thread?
Difference between buffer and cache?
Ways to swap without using temporary variable 

where are the USB drivers installed in Linux.  

Describe DHCP DORA, Entire OSI stack, In depth DNS and DHCP, Wireshark process, ARP, HTTP etc.  

I have a planned incoming DDoS attack against a network, what measures would you put in place to mitigate this? Why would you put these measures in place, what is the benefit vs cost?  
1. PC is not booting up, what may be the possible reasons?
2. You are browsing two different things on the same browser how it will be defined which packets of data have to be sent where?

Troubleshooting a slow download issue on PC  

Troubleshooting a PC that doesn't boots up.  

Assigning IP address to PCs.  

How www.amazon.com is accessed, in detail. Explain what happens to packet at each OSI layer.  

TCP/UDP. Why TCP.  

OS concepts: Paging, TLB, Deadlocks, Virtual Memory, Virtualization, Memory Management  

BSOD, Mac troubleshooting, Process management, Hardware troubleshooting, Network Adapter troubleshooting, NIC troubleshooting, RAID troubleshooting etc.  

Public/private ip, static/dynamic ip whar are they, differences.
What happens when you type in browser amazon.com?
Which part is the domain name? Subdomain?
Tcp/udp differences? Use areas?
Http codes?
Dhcp?
Tcp handshake? How to disconnect?

What is a virtual memory?

If someone comes to you with a slow computer what do you do? -check task manager, antivirus, disk fragmentation.
Bluescreen, causes etc.
What is on device manager?

Linux commands: list directory, change directory, check permission?  
ports used by various protocols
DHCP
DNS
boot loading
ping and tracerouter mechanism
slow connection troubleshooting  



What is Active Directory?
Difference between static and dynamic routing
A client in Germany is trying to access a server in London, but his connection is running slow. You are in Dublin. How do you diagnose his issue?  
1. common ports 2. active directory 3. IPsec 4. DHCP 5. DNS  

Database :

Knowing the SQL Queries
Knowing about joins,subqueries,constraints etc.
Basic database troubleshooting (Like Can’t login, Can’t connect to the database)
Basic RDMS concept (they can refer tutorial point for the same DBMS topic)
Networking :

· Difference between router, switch.

· What is a Broadcast Domain?

· DHCP DORA process

· DNS – detailed explanation. TCP/UDP and why?

· Subnetting

· MSS/MTU

· Complete flow when you trigger amazon.com

· OSI model with complete details and protocols on each layer.

· TCP and SSL handshake

· Difference between TCP/UDP, examples

· Flow/error control

· What is a firewall, why do you need it?

· OSI Model

OS :

         OS boot process (Win/Linux)

- Memory management ;Memory pages; Buffer and Caches, Basic commands
------------------------------

- My net isn't working, how do i troubleshoot?
- My net speed is slow, i need you to troubleshoot
- Whats ptr entry in DNS.
-Explain DNS, DHCP, Memory management to your grand father.
-Have you dealt with a bad customer?
-Any decisions that you regret?
Etc..  

Can you explain the DNS system?  

basic linux system administration questions

what is difference between TCP and UDP. give a application example for each.  

Difference between Raid2 or RAID5, mdadm. Raid and logical volume.

LP Questions 

https://www.rooftopslushie.com/request/Amazon-Leadership-Principles-Interview-Questions-149

Windows, Linux and network troubleshooting, internet basics-blues screen, slow network, http error codes etc

Windows, Linux and network troubleshooting, internet basics-blues screen, slow network, http error codes etc

If a server failed to do a nightly backup, what could be a reason for that?  

Answer : May be due to failure or mis-configuration of NTP Server. (Check in google)

basics of networking questions.

Basics of network troubleshooting and a few questions on clustering.  

They are basically checking our knowledge on troubleshooting issues and customer service. Computer network related questions are asked.

What happens when you type amazon.com in the browser?
Linux server troubleshooting steps .
What is DNS ?
Explain IPsec briefly.
What are problems you found with AWS
How to deal with an angry customer.
How to handle problems like CPU is 100% occupied or the computer is slow what are the possible problems?  

Basic Networking questions:
What is the difference between Bandwidth, Delay and Latency?
What is MTU, Window Size, Segment (MSS)?
Describe 3-way handshake.
A scenario question about prefix-match and route summarization
A scenario question about Stateful/Stateless firewall.
A scenario question about packet flow in NAT
How DNS work
How DHCP work
What is BGP and describe the states - Idle, Connect, Active, Opensent, Openconfirm, Established.
Tell me a time you went out of your way to do something amazing for a client.
Do you have any question for me?  

what is Active Directory and why would anyone use it?
importance of time in a Windows domain
what is sysprep, sysvol, BSoD, DHCP, DNS, DFSR, WINS, Global Catalog,
Describe built-in tools to troubleshoot network issues.
Some best security practices and a scenario on a company under DoS attack and you choose best answers or suggest any additional answer.
Finally, A bonus project to build a system that is robust and fault-tolerance for a start-up ecommerce website. .  

expliain 3 way handshake  

Explain how DNS works  

how to troubleshoot a slow computer, past project i am proud about, how to deal with a data loss complain from a client,  

how you reach to amazon.com, tell me layer vise. What is DNS? Explain all the steps for DNS. What protocol is used and how it is used to gate out from private network.(ARP)? website is slow how will you troubleshoot ? What is TCP? What is UDP? TCP three way handshake process. Basic l2,l3, some more networking, web servers, windows trouble shooting test, dns server questions.
Why Amazon?   … 

Questions related to NAT, DNS, EIGRP. He even asked Linux based questions like what commands will you use to find the disk space, how would you use puppet to execute a command, how would you troubleshoot if ssh is not working.

What is the difference between range and xrange in python.  

HTTP codes.  

 basic networks,Linux commands and operating systems.

Hypervisor, VmWare, windows troubleshooting (blue screen of death), DNS, DHCP, what happens when we type www.amazon.com, linux commands (basics since I told Im good in windows), what will you do when you type a website and website isn't coming (how do you troubleshoot?), Active directories in Windows Server, how would you handle a customer who complains that all his data has been lost and no when theres no back up?, difference between cloud and traditional services, what would you improve in AWS? how would you design your web application on AWS? He told next would be onsite if I was selected, but sadly I didnt get selected.

Debugging skills on a webpage nor being found.
Linux based rounds where they ask you lot on commands
Basic networking stuff with http, dns in particular.  

operating systems questions were difficult  

Linux server troubleshooting steps
What is DNS?
Steps for resolving www.amazon.com
What is DHCP?
Explain IPsec briefly  

What are problems you found with AWS?  

Technical -
  questions about DNS, DHCP process, TCP/UDP, entire stack and functions of each layer, Active directory, web servers, linux configurations, object oriented programming concepts.
Some behavioral skills were also tested by giving some situations.

Behavioral -
   Be ready to tell stories about your past work experience and projects to all the behavioral questions. They write down everything you say so be good at it. Leadership qualities are stressed the most. Handling conflicts, handling failures, misjudgement etc are some of the situations. Think over before you start answering. Also prepare for questions like why do you want to work with amazon? what do you want to do?  

Explain DNS
What is DHCP  

1. What happens when you type amazon.com in the browser? ( was asked two times by different interviewers)
2. Phone interview was pleasant and the questions were troubleshooting issues
3. Database administration interview was tough for me. though the questions were simple i was not prepared for a DBA questionnaire.
4. Behavioral questions are pretty straight forward and the interviewers would like to know the experience of you in situations like challenging project/task. be prepared to what you have to answer.
5. Dont leave out to revise on the simple points such as common ports, DBA questions etc.
6. What and how the load value is calculated which is displayed when you give the command "uptime"?  

Mostly on my past experience and routing protocol related questions.  

In what order are group policies applied in Active Directory?  

TCP/ IP Stack, DNS, DHCP, IP routing, troubleshooting scenarios  

Troubleshoot a user's connection problems.  

know the basics of networking like TCP, UDP, routing protocols, and also how to troubleshoot a network. Know how ping and traceroute work etc.
On the behavioral side, just be yourself. Show them that you can handle difficult situations, and give examples. While giving examples, don't say "we did", talk about what "you" did. Use "I" a lot.  

Networking(TCP, UDP, IP, HTTP), some Linux OS  

tech: networking basic: tcp, dns, amazon.com resolution, linux commands, linux troubleshooting basics.

Why Amazon  

How to reach Amazon?
TCP 3 way handshake?
Why amazon?
Difference between TCP and UDP?  

Online Assesement covers IP/TCP, Subneting, Troubleshooting, Private/Public IPs, Routing, Linux Commands like iostat,vmstat, crontab, free, proc/meminfo etc.
Phone Interview: Is 1.1.1.1 routable? What are private IPs ( Ranges)? Are the private IPs submask Classless and Classful? How will you troubleshoot slow website? What linux command to check open ports?  

Most of the questions were based on Linux commands to test the network and IP address range. 

DNS, Basic linux commands, Leadership principles and please go through all the interview questions from glassdoor, they were really helpful.  

Networking -- covered TCP/ IP , TCP handshake, Layer 3 protocols

Linux -- How do you troubleshoot a Server? and other following questions based on that.
                   Linux commands
"I have forgotten my password, how will you help me?"  

Behavioral : Focus solely on Amazon 14 Principles and relate iIf you type example.com and it doesn't open what would you do?  

t to your experience  

What happens when you press the power button on your PC?  

HTTP codes 404, 403, 200  

1. Difference between DNS and IP? 2. Private IP vs Public IP? 3. Cloud v Vitualization 4. How to handle problems like CPU is 100% occupied or the computer is slow what are the possible problems?  

What is Linux boot up process?  

Why do you want to come and work at Amazon?  

Databases Concepts
Networking Concepts
Amazon Leadership Principles 

A client in Germany is trying to access a server in London, but his connection is running slow. You are in Dublin. How do you diagnose his issue?  

How do you find out what your IP Address is?  

Network troubleshooting commands  

Preemptive Multithreading  What is nslookup?

What is fstab?  

Docker basic commands and working.
2.Differences between chef-solo and chef-zero.
3.Git Basics
4. Grep, nslookup, commands
5. poymorphism,encapsulation and abstraction  

What happens when you type an address into a browser and press enter  

How to setup remote desktop connection using command line in windows  

When you type a URL into your web browser, what happens when you press enter?  

Windows administration. Windows and linux commands. DNS resolution in detail.  

Make sure you know the OSI model and dns very well.  

what is the difference about UDP and TCP, what kind of application base on UDP
what is FTP? what kind of application it used for?
what the different between HTTP and HTTPS? and why HTTPs more secure?

Hash Table Introduction

Hash Table is a data structure which organizes the data using hash functions in order to support quick insertion and search.


We have two different types of hash tables :

1. HashSet

2. HashMap

-> HashSet is one of the implementation of Set Data Structure with no repeated values.

-> HashMap is one of the implementation of Map Data Structure to store (Key , Value ) pairs.

By using proper hash function the hash table can achieve wonderful performance in both insertion and search.


Principle Behind the Hash Table :

Hash Table is a data structure which supports quick insertion and search using hash functions.

The Key idea of the hash function is to map keys to buckets .

1. When we insert a new key the hash function will decide which bucket the key should be assigned and the key will be inserted into the corresponding bucket.

2. When we want to search for a key , the hash table  will use the same hash function to find the corresponding bucket and search only in the specified bucket.



For Example consider Y = X % 5 is our hash function .


Consider the elements ->  3 . 5 . 6  7  10


All the elements will go through the hash function and will get mapped to the corresponding buckets.

Insertion :

So . 3 will be assigned to bucket with index 3.

       5 . will be assigned to bucket with index 0.

      6   will be assigned to bucket with index 1.
   
      7 will be assigned to bucket with index 2.
 
     10 will be assigned to bucket with index 0.

Search:

We parse the elements through the same hash function and search in the specified bucket.

 If we want to search 23 we will search in bucket 3 as 23%5 is 3.

If we want to search 34 we will search in bucket 4 as 34%5 is 4.

Summary Of LinkedList

Review of SinglyLinkedList and DoublyLinkedList :

1. Both of them not able to access the data at random position in constant time.

2. Both of them are able to add a node at the beginning of the list or add a node after a given node in O(1) time.

3. Both of them are able to delete first node in O(1) time.

But it is little different in deleting the given node (Including the last node).

-> In a singly linked list , it is not able to get the previous node in constant time , we have to spend O(N) time to find out the previous node before deleting the given node.

-> In a doubly linked list , it is much easier because we delete a node using the prev reference field in O(1) time.


Time comparison

Conclusion :

If you want to delete or add a node in a linked list will be the better choice.

If you want to access an element in an array in constant time then array will be best.

Design Doubly Linked List - Solution

// Definition of Doubly Linked List

class DoublyListNode {
int val;
DoublyListNode prev, next;
DoublyListNode(int x){
val = x;
}
}

// Initiate a new Linked List

class MyLinkedList {

private DoublyListNode head;

public MyLinkedList(){
head = null;
}
}

// Traversing the Linked List to get element by index.

private DoublyListNode getNode(int index){
DoublyListNode cur = head;

for(int i=0 ; i < index && cur != null ; i++){
cur = cur.next;
}
return cur;
}


// Function to return last Node of the linked list

private DoublyLinkedList getTail(){

DoublyListNode cur = head;

while(cur !=null && cur.next !=null){
cur = cur.next;
}
return cur;
}


// To fetch the value of the index-th node in the linked list

private int get(int index){

DoublyListNode cur = getNode(index);
return cur == null ? -1 : cur.val;
}


// Add a new Node

// Add a Node if the DoublyListNode is null and add at Head.
public void addAtHead(int val){
DoublyListNode cur = new DoublyListNode(val);
cur.next = head;
if(head != null){
head.prev = cur;
}
head = cur;
return;
}

// Add a Node at Tail 

public void addAtTail (int val){
DoublyListNode prev = getTail();
DoublyListNode cur = new DoublyListNode(val);
if(head == null){
addAtHead(cur);
return;
}
prev.next = cur;
cur.prev = prev;
}

// public void addAtIndex (int index , int val){
if(index == 0){
addAtHead(val);
return;
}

DoublyListNode prev = getNode(index-1);
if(prev == null){
return;
}

DoublyListNode cur = new DoublyListNode(val);
DoublyListNode next = prev.next;

cur.prev = prev;
cur.next = next;
prev.next = cur;
if(next !=null)
next.prev = cur;
}

}

Similar to the SinglyLinkedList it takes O(N) time to get a node by index. where N is the length of the linked list.


// Delete a Node

public void deleteAtIndex (int index){

DoublyListNode cur = get(index);
DoublyListNode prev = cur.prev;
DoublyListNode next = cur.next;

if(cur == null)
return;

if(prev != null){
prev.next = next;
} else {
head = next;
}

if(next != null){
next.prev = prev;
}

}

Introduction To Doubly Linked List

In previous article we learned about SinglyLinkedList.

https://techyield.blogspot.com/2019/06/singly-linked-list-introduction.html

Here we are going to discuss about DoublyLinkedList.

In SinglyLinkedList we have a value field and a reference field to the next node.

In DoublyLinkedList we have one extra field called prev node which points to the prev node. With this field we are able to know the previous node of the current node.


Node Structure :

class DoublyListNode {

int val;
DoublyListNode prev , next;

DoublyListNode(int x){
val = x;
}

}

The entire list is represented with the head node as in SinglyLinkedList.


Operations :

Add Operation :

If we want to insert cur after an existing node prev  .

We can add in two steps :

1. Link cur with prev and next , where next is the original next node of prev.

2. Re link the prev and next with cur.

Similar to the singly Linked List the space and time complexity is O(1).

Delete Operation :

If we want to delete an existing node cur from the doubly linked list we can simply link its prev node prev with the next node next.

Unlike the singly linked list it is easy to get the prev field in constant time O(1).

Here the space and time complexity both are O(1).