Blog (Notes)

Let us quickly go through some important concepts related to subnets:

• A network may be divided into sub networks for easy maintenance and security concerns. These sub networks are referred to as subnets.

• Additional bits from the HID will be used for subnetting. The netmask for a subnet will represent the combination of NID bits (without subnet identifier bits) and subnet identifier bits, and this combined bit mask is usually called a subnet mask. 

Let us first quickly go through some important concepts related to IP addresses and CIDR:

• An IPv4 address has 32 bits divided into 4 octets (Each octet consist of 8 bits). Each part (octet of bits) is represented in their decimal form separated by dots. E.g. 10.12.14.16. This format is referred to as dotted decimal format. 

• The maximum decimal number that any of the four parts of an IPv4 address can hold is 255 as the largest binary number that can be represented by 8 bits is 11111111.

Following are some of the most important points related to Public Key Infrastructure (PKI) for passing exams and for general understanding.

• Public Key Infrastructure (PKI) is a set of tools, protocols, processes, polices etc. that can help us to do secure communication using public key encryption.

Following are some of the most important points related to encryption for passing exams and for general understanding.

Following are some of the most important points related to digital certificates and hashing, for passing exams and for general understanding.

Following are some of the most important points related to asymmetric encryption for passing exams and for general understanding.

• Asymmetric Encryption uses two mathematically related but different keys known as a key pair.

• The key pair within an asymmetric encryption is commonly referred to as a private key and a public key. 

• In Asymmetric encryption, we can encrypt with one of the keys in the key pair and then decrypt with the other key in the key pair.

A Binary formula quick reference can help in many cases, especially when we are dealing with IP addresses for first time. The more and more you use them the need to look into the table will become less and less.

Useful Formulas

2^a * 2^b = 2^a+b. For example 2² * 2⁸ = 2^10.

2^a + 2^a = 2 * 2^a = 2^1+a. For example 2¹¹ + 2¹¹ = 2^12.

Here are some userful resources to learn deeper about computer networking concepts.

• Computer Networks - Gate Lectures by Ravindrababu Ravula

A Binary to Decimal quick reference can help in many cases, especially when we are dealing with IP addresses for first time. The more and more you use them the need to look into the table will become less and less.

Powers of 2

• 2¹ = 2

• 2² = 4

• 2³ = 8

• 2⁴ = 16

• 2⁵ = 32

• 2⁶ = 64

• 2⁷ = 128

Whenever you add reviews for the book, please follow below rules.

1. Write issues in an excel.

2. Create an excel per chapter (or one tab per chapter).

3. Create following columns: Issue, Recipe, H2 Heading, H3 Heading (If Any), Paragraph Number, Line Number, Reporter, CAdmin Remarks, Verification.

Notes:

1. Paragraph number is within the last heading (H2 or H3).

2. Line number is within the current paragraph.

3. Reporter is your first name.