Certificate : AWS Certified Solutions Architect course completed

Finished “AWS Certified Solutions Architect” online course from Udemy 🙂

This certificate above verifies that Aseem Jain successfully completed the course AWS Certified Solutions Architect – Associate 2019 on 06/28/2019 as taught by Zeal Vora on Udemy. The certificate indicates the entire course was completed as validated by the student.


cloud: Internet is Mesh topology

Internet is Mesh topology. read more to understand 😉

Star topology is singe point of failure, which mean all the devices are connected to hub connected as the center of star with single wire. If hub / switch fails network will go down.

Our home wifi works on wireless star topology, where in all cellphone/devices are connected to router as center of star.

In Mesh topology, one devices is connected with several other devices using multiple wires. (wire mesh). That way if one hub fails, network still works.

Mesh topology is opposite of single point of failure and is redundant, which means even if one router fails, data packet can be relayed or routed using different route or path. Imagine a big house with one in modem and router with multiple wifi extenders, that way if range is week for one extenders, data can still travel using other extender device to reach to modem 🙂

Cloud: DDoS Attack Explained

In computing, a denial-of-service attack is a cyber-attack in which the perpetrator seeks to make a machine or network resource unavailable to its intended users by temporarily or indefinitely disrupting services of a host connected to the Internet. 

You can spin up thousands cloud servers for 2 hours and attach a server from several sources at specific time. Spot instance from AWS would be cheap. Since attack will come from different ips the target server will not be able to stop it easily.

Use different cloud providers, use different regions but start running the army of computer at the same time.

Cloud: what is mac address and how ARP resolves it

Mac address is the unique unchangeable address give to each network address. Technically mac address the real address, ip address is temprary, as you change your address your ip address will change but not your mac address ( when you use airport free wifi your ip is difference)

media access control address (MAC address) is a unique identifier assigned to network interfaces for communications on the physical network segment. MAC addresses are used as a network address for most IEEE 802 network technologies, including Ethernet. Logically, MAC addresses are used in the media access control protocol sublayer of the OSI reference model.

MAC addresses are most often assigned by the manufacturer of a network interface controller (NIC) and are stored in its hardware, such as the card’s read-only memory or some other firmware mechanism.

This is strange but true that all the devices in you home have same public ip address 😉 and that is the public ip of your router provided dynamically by your ISP.

ARP is Address resolution protocol which would help to resolve the public + private ip into a mac address. This get cached as well, so that whenever the communication happens the sender targets it towards mac address

cloud: NAT Explained – Network Address Translation

NAT => Network address translation

In my house my router has been assigned dynamically a public ip, all my devices in home have a private ip address. Think of it as phone number for a company with phone extension for each employee. Hence it is responsibility of NAT ( acts like telephone receptionist) to translate private + public ip and establish the connection.

with ipv6, we do not need NAT any more 😉 since ipv4 are only 4 billion hows ipv6 which is 128 bits has delizzions ( more then billion, zillion etc) ip range available. But who knows we might even exhaust that too in future 😉