Notes

Router
Switch
Modem
TCP/IP - 3 Way handshake. Syn, Syn-Ack, Ack - Data transmission and Fin( terminate connection automatic), header 20 bytes.
UDP - header 8 bytes
Packet
Socket - Combination of both port and IP Address. communication happens between sockets. Like from a Server to Client.
Port - lower 1024 ports are used for well known services. Ephemeral ports are higher number ports.
* There are 65535 ports available.
** OSI Model
1. Physical Layer: Lowest Layer in the OSI model (Open Systems Interconnection). Contains information in the form of bits.
2. Data Link Layer: Packets are referred to as Frames. Framing is the function of DLL. LLC and MAC ( Logical Link Control and Media Access Control). Data is error free from one node to another. DLL transmits packets using the MAC Address.
3. Network Layer: Packet Routing in same or different network. sender and receiver IP addresses are placed in the header. segments are referred as packets.
4. Transport Layer - Data is referred to as segments. Responsible for end to end delivery of complete message. ack of data transmission and re-transmit if errors. Connection oriented and connection-less transmission
5. Session Layer - establishes connection, maintains sessions, authentication and security.
6. Presentation Layer - also known as translation layer. used for translation ( ascii to other codes), encryption/decryption, compression
7. Application Layer - browser, messenger etc.., displays information to the users.

** RAID levels: Raid0 - Striping, 1 - Mirroring , 2 - bit level Striping with hamming-code parity, 3 - Striping with dedicated parity, 4-Block level striping with dedicated parity, 5 - Striping with Parity,Parity bits are distributed evenly on all disks after each sequence of data has been saved, Therefore, RAID 5 provides redundancy through parity bits instead of mirroring. min 3 disks and upto 16 disks....6 - Striping with double parity, min 4 disks, can handle data recovery even if two disks fail.
**LB
** Relational and NOSQL dbs: RDBMS are Structured, data is stored in tables, Requires schema to be defined before the data is stored.
** How do you troubleshoot slow db
**OLAP and OLTP: Online Analytical processing Vs Online Transaction processing.
** CI/CD concept: Continuous Integration/Continuous Delivery/Deployment. Faster Agile Development and deployment.
** CDN: Content delivery networks.
** Identity federation HTTPS/SSL
**Diff between layer 2 and 3
**DNS what is the process
** server performance
** ssl/http/https
**When have you ever taken a risk, made a mistake or failed? How did you respond and how did you learn from that experience? Tell me about a time when you had to make a quick decision that was going to have a significant impact on the organization? Describe a situation when you had to work with incomplete data or information Give me two examples of when you have gone above or beyond what was expected?
STAR Questions:
When you faced big challenge?

AWS Cloud Benefits: Make sure you read the 6 advantages of cloud computing by AWS and be able to explain these concepts and how they are advantageous to companies.
** stop spending money for maintaining infrastructure, data center and serverless, pay as you go, increase speed and agility, deploy globally, capacity planning
Compute services: Amazon EC2, AWS Elastic Beanstalk, AWS Lambda, Amazon EC2 Auto Scaling, Amazon Elastic Load Balancing and AWS LightSail.
Storage services: Amazon S3, Amazon EBS, Amazon EFS, AWS Storage Gateway, Amazon S3 Glacier.
Networking: Amazon VPC, route tables, security groups, network ACLs, AWS Direct Connect, Amazon VPN, AWS Transit Gateway.
Content delivery and acceleration: AWS CloudFront and AWS Global Accelerator – make sure you’re clear on the differences and use cases.
Databases: Amazon RDS, Amazon DynamoDB, Amazon ElastiCache, Amazon EMR.
AWS Global Infrastructure: Make sure you can easily explain the differences between AWS Regions, Availability Zones, Edge Locations, Regional Edge Caches and AWS Local Zones.
Migrating to the cloud: Be able to explain hybrid cloud scenarios and the AWS tools companies can use to migrate servers, storage and databases into AWS.
AWS Well Architected Framework: Make sure you understand the 5 pillars of the well architected framework ahead of your interview.


Leadership Principles:
1. Customer Obsession
2.Ownership
3. Invent & Simplify
4.Are Right, a lot
5. Learn and be curious
6.Hire and Develop the best
7. Insist on High Standards
8.Think Big
9. Bias for action
10, Frugality
11. Earn Trust
12. Dive Deep
13.Have backbone, Disagree and Commit
14. Deliver Results.
15. Strive to be earths best employer
16. Success and Scale big broad responsibility.