Merge pull request #72 from austinsonger/master

ANSWERED Network Related

README.md

@@ -30,7 +30,7 @@
   <tr>
     <td align="center"><a href="#coding"><img src="images/coding.png" width="75px;" height="75px;" alt="coding"/><br /><b>Coding</b></a><br /><sub><a href="#coding-beginner">Beginner :baby:</a></sub><br><sub><a href="#coding-advanced">Advanced :star:</a></sub></td>
     <td align="center"><a href="#python"><img src="images/python.png" width="80px;" height="75px;" alt="Python"/><br /><b>Python</b></a><br /><sub><a href="#python-beginner">Beginner :baby:</a></sub><br><sub><a href="#python-advanced">Advanced :star:</a></sub></td>
-    <td align="center"><a href="#go"><b>Go</b></a><br /><sub><a href="#go-beginner">Beginner :baby:</a></sub><br><sub></td>
+    <td align="center"><a href="#go"><img src="images/Go.png" width="75px;" height="75px;" alt="go"/><br /><b>Go</b></a><br /><sub><a href="#go-beginner">Beginner :baby:</a></sub><br><sub></td>
     <td align="center"><a href="#shell-scripting"><img src="images/bash.png" width="70px;" height="75px;" alt="Bash"/><br /><b>Shell Scripting</b></a><br /><sub><a href="#shell-scripting-beginner">Beginner :baby:</a></sub><br><sub><a href="#shell-scripting-advanced">Advanced :star:</a></sub></td>
     <td align="center"><a href="#kubernetes"><img src="images/kubernetes.png" width="75px;" height="75px;" alt="kubernetes"/><br /><b>Kubernetes</b></a><br /><sub><a href="#kubernetes-beginner">Beginner :baby:</a></sub><br><sub></td>
     <td align="center"><a href="#prometheus"><img src="images/prometheus.png" width="75px;" height="75px;" alt="Prometheus"/><br /><b>Prometheus</b></a><br /><sub><a href="#prometheus-beginner">Beginner :baby:</a></sub><br><sub><a href="#prometheus-advanced">Advanced :star:</a></sub></td>
@@ -39,8 +39,8 @@
   </tr>
   <tr>
     <td align="center"><a href="#cloud"><img src="images/cloud.png" width="110px;" height="75px;" alt="Cloud"/><br /><b>Cloud</b></a><br /><sub><a href="#cloud-beginner">Beginner :baby:</a></sub><br><sub></td>
-    <td align="center"><a href="#aws"><b>AWS</b></a><br /><sub><a href="#aws-beginner">Beginner :baby:</a></sub><br><sub></td>
+    <td align="center"><a href="#aws"><img src="images/aws.jpg" width="75px;" height="75px;" alt="aws"/><br /><b>AWS</b></a><br /><sub><a href="#aws-beginner">Beginner :baby:</a></sub><br><sub></td>
-    <td align="center"><a href="#azure"><b>Azure</b></a><br /><sub><a href="#azure-beginner">Beginner :baby:</a></sub><br><sub></td>
+    <td align="center"><a href="#azure"><img src="images/azure.png" width="75px;" height="75px;" alt="azure"/><br /><b>Azure</b></a><br /><sub><a href="#azure-beginner">Beginner :baby:</a></sub><br><sub></td>
     <td align="center"><a href="#gcp"><b>Google Cloud Platform</b></a><br /><sub><a href="#gcp-beginner">Beginner :baby:</a></sub><br><sub></td>
     <td align="center"><a href="#openstack"><img src="images/openstack.png" width="75px;" height="75px;" alt="openstack"/><br /><b>OpenStack</b></a><br /><sub><a href="#openstack-beginner">Beginner :baby:</a></sub><br><sub><a href="#openstack-advanced">Advanced :star:</a></sub></td>
     <td align="center"><a href="#security"><img src="images/security.png" width="75px;" height="75px;" alt="security"/><br /><b>Security</b></a><br /><sub><a href="#security-beginner">Beginner :baby:</a></sub><br><sub><a href="#security-advanced">Advanced :star:</a></sub></td>
@@ -819,10 +819,19 @@ AWS CloudTrail
 
 <details>
 <summary>What is Ethernet?</summary><br><b>
+
+Ethernet simply refers to the most common type of Local Area Network (LAN) used today. A LAN—in contrast to a WAN (Wide Area Network), which spans a larger geographical area—is a connected network of computers in a small area, like your office, college campus, or even home.
 </b></details>
 
 <details>
 <summary>What is a MAC address? What is it used for?</summary><br><b>
+
+A MAC address is a unique identification number or code used to identify individual devices on the network.
+
+Packets that are sent on the ethernet are always coming from a MAC address and sent to a MAC address. If a network adapter is receiving a packet, it is comparing the packet’s destination MAC address to the adapter’s own MAC address.
+
+
+
 </b></details>
 
 <details>
@@ -831,10 +840,41 @@ AWS CloudTrail
 
 <details>
 <summary>What is an IP address?</summary><br><b>
+
+An Internet Protocol address (IP address) is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication.An IP address serves two main functions: host or network interface identification and location addressing.
+
+
 </b></details>
 
 <details>
 <summary>Explain subnet mask and given an example</summary><br><b>
+
+A Subnet mask is a 32-bit number that masks an IP address, and divides the IP address into network address and host address. Subnet Mask is made by setting network bits to all "1"s and setting host bits to all "0"s. Within a given network, two host addresses are reserved for special purpose, and cannot be assigned to hosts. The "0" address is assigned a network address and "255" is assigned to a broadcast address, and they cannot be assigned to hosts.
+
+**For Example**
+
+```
+| Address Class | No of Network Bits | No of Host Bits | Subnet mask     | CIDR notation |
+| ------------- | ------------------ | --------------- | --------------- | ------------- |
+| A             | 8                  | 24              | 255.0.0.0       | /8            |
+| A             | 9                  | 23              | 255.128.0.0     | /9            |
+| A             | 12                 | 20              | 255.240.0.0     | /12           |
+| A             | 14                 | 18              | 255.252.0.0     | /14           |
+| B             | 16                 | 16              | 255.255.0.0     | /16           |
+| B             | 17                 | 15              | 255.255.128.0   | /17           |
+| B             | 20                 | 12              | 255.255.240.0   | /20           |
+| B             | 22                 | 10              | 255.255.252.0   | /22           |
+| C             | 24                 | 8               | 255.255.255.0   | /24           |
+| C             | 25                 | 7               | 255.255.255.128 | /25           |
+| C             | 28                 | 4               | 255.255.255.240 | /28           |
+| C             | 30                 | 2               | 255.255.255.252 | /30           |
+
+```
+
+### 
+
+
+
 </b></details>
 
 <details>
@@ -844,13 +884,14 @@ AWS CloudTrail
 <details>
 <summary>Explain the OSI model. What layers there are? What each layer is responsible for?</summary><br><b>
 
-Application: user end (HTTP is here)
+- Application: user end (HTTP is here)
-Presentation: establishes context between application-layer entities (Encryption is here)
+- Presentation: establishes context between application-layer entities (Encryption is here)
-Session: establishes, manages and terminates the connections
+- Session: establishes, manages and terminates the connections
-Transport: transfers variable-length data sequences from a source to a destination host (TCP & UDP are here)
+- Transport: transfers variable-length data sequences from a source to a destination host (TCP & UDP are here)
-Network: transfers datagrams from one network to another (IP is here)
+- Network: transfers datagrams from one network to another (IP is here)
-Data link: provides a link between two directly connected nodes (MAC is here)
+- Data link: provides a link between two directly connected nodes (MAC is here)
-Physical: the electrical and physical spec the data connection (Bits are here)
+- Physical: the electrical and physical spec the data connection (Bits are here)
+
 </b></details>
 
 <details>
@@ -902,18 +943,44 @@ CSMA/CD algorithm:
 
 <details>
 <summary>How does a router works?</summary><br><b>
+
+A router is a physical or virtual appliance that passes information between two or more packet-switched computer networks. A router inspects a given data packet's destination Internet Protocol address (IP address), calculates the best way for it to reach its destination and then forwards it accordingly.
+
+
 </b></details>
 
 <details>
 <summary>What is NAT?</summary><br><b>
+
+ Network Address Translation (NAT) is a process in which one or more local IP address is translated into one or more Global IP address and vice versa in order to provide Internet access to the local hosts. 
+
+
 </b></details>
 
 <details>
 <summary>What is a proxy? How it works? What do we need it for?</summary><br><b>
+
+A proxy server acts as a gateway between you and the internet. It’s an intermediary server separating end users from the websites they browse.
+
+If you’re using a proxy server, internet traffic flows through the proxy server on its way to the address you requested. The request then comes back through that same proxy server (there are exceptions to this rule), and then the proxy server forwards the data received from the website to you.
+
+roxy servers provide varying levels of functionality, security, and privacy depending on your use case, needs, or company policy.
+
+
 </b></details>
 
 <details>
 <summary>What is TCP? How it works? What is the 3 way handshake?</summary><br><b>
+
+TCP 3-way handshake or three-way handshake is a process which is used in a TCP/IP network to make a connection between server and client.
+
+A three-way handshake is primarily used to create a TCP socket connection. It works when:
+
+- A client node sends a SYN data packet over an IP network to a server on the same or an external network. The objective of this packet is to ask/infer if the server is open for new connections.
+- The target server must have open ports that can accept and initiate new connections. When the server receives the SYN packet from the client node, it responds and returns a confirmation receipt – the ACK packet or SYN/ACK packet.
+- The client node receives the SYN/ACK from the server and responds with an ACK packet.
+
+
 </b></details>
 
 <details>
@@ -928,6 +995,10 @@ TCP establishes a connection between the client and the server to guarantee the
 
 <details>
 <summary>True or False? TCP is better than UDP</summary><br><b>
+
+False. 
+UDP is faster, simpler and more efficient than TCP
+
 </b></details>
 
 <details>
@@ -936,10 +1007,20 @@ TCP establishes a connection between the client and the server to guarantee the
 
 <details>
 <summary>Explain "default gateway"</summary><br><b>
+
+A default gateway serves as an access point or IP router that a networked computer uses to send information to a computer in another network or the internet.
+
+
 </b></details>
 
 <details>
 <summary>What is ARP? How it works?</summary><br><b>
+
+ARP stands for Address Resolution Protocol. When you try to ping an IP address on your local network, say 192.168.1.1, your system has to turn the IP address 192.168.1.1 into a MAC address. This involves using ARP to resolve the address, hence its name.
+
+Systems keep an ARP look-up table where they store information about what IP addresses are associated with what MAC addresses. When trying to send a packet to an IP address, the system will first consult this table to see if it already knows the MAC address. If there is a value cached, ARP is not used.
+
+
 </b></details>
 
 <details>