CIDR block representation practice question

Duration: 4 min

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Inside: a video lesson and guided study material.

Module outline

  1. Paper 1 | Reasoning Test: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Syllogisms, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Seating Arrangements, Blood Relations, Puzzle Solving (Puzzles), Venn Diagram, Analogy, Ranking, Order and Sequence, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Selection Decision Table (Decision Making), Logical Sequence Of Words, Cubes & Dices, Analytical Reasoning (Counting Figures Reasoning), Calendar, Alphabet and Word Tests, Numerical Reasoning, Number System, Averages, Mixtures and Alligation, Percentages, Series Completion, Analogy and Classification, Patterns in Two-Dimensional Figures, Coding and Decoding, Mathematical Operations, Direction Sense, Algebra, Logical Deduction and Induction, Syllogisms and Venn Diagrams, Critical Reasoning, Order, Ranking and Sequence, Reading Comprehension, Profit, Loss and Discount, Constraint Puzzles, Speed, Time and Distance, Traverse Surveying, Ratio and Proportion, Time and Work, Mensuration, Permutations and Combinations, Clocks and Calendars, Data Interpretation, Assembling and Grouping of Shapes, Transformation of Shapes, Three-Dimensional Patterns and Visualization, Cubes and Dice, Vocabulary, Blood Relations, Data Sufficiency
  2. Paper 1 | Numerical Analysis: Number System, HCF LCM, Percentage, Ratio and Proportion (Ratios), Average, Sequence and Series (Series), Powers and Exponents (Surds and Indices), Algebra, Statistics, Data Interpretation, Mental Ability, Arithmetic, Logarithm, Profit and Loss, Simple Interest and Compound Interest, Speed Time and Distance, Mixture and Alligation, Mensuration and Geometry, Permutation and Combination, Probability, Sequences and Series, Powers, Surds and Logarithms, Subject-Verb Agreement, Sentence Completion, Geometry, Sentence Structure and Correction, Data Sufficiency, Trigonometry, Measurement and Quantity Take-Off, Signal Space and Optimum Detection, Probability, Statistics, Algebra, Time and Work, Speed, Time and Distance, Data Interpretation, Graph Theory, Combinatorics
  3. Paper 1 | General Knowledge: State Wise GK, History, Geography, GK- Current Affairs, Static General Knowledge, Polity, Indian Economy
  4. Paper 1 | DBMS: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, File Organization & Indexing, Relational Algebra, SQL, Transaction Management, Concurrency Control, Relational Calculus, Database Security & Authorization, Database Recovery
  5. Paper 1 | Data Communication & Network: Introduction to CN, Data Communication, DLL: Access Control, DLL: Flow Control, DLL: Error Control, DLL: Framing, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Net Layer:Routing Protocol, Transport Layer Services, TL: Congestion & UDP, Application Layer, Network Security, Security in Mobile and Wireless Computing, Input Output Organisation, File Management, Hardware Basics, Terms & Abbreviations, Protocols & Services, Network Access Technologies, Cyber Safety and Security, Basics of COA
  6. Paper 2 | System Analysis & Design: Fundamentals of Systems and Information Systems, SDLC and Development Approaches, Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Documentation and Software Requirements Specification (SRS), SDD and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management, Security, Risk Management & Maintenance, extras
  7. Paper 2 | Programming Language (Java): Java Fundamentals, OOPS with Java, Array, String, IO & References, Generic & Collections, Multithreading, Java, Miscellaneous, Control Flow, OOPS with C++, Stack, C Fundamentals, Arrays & Pointers, Object Oriented Technology, Control Flow & Looping, Introduction to Python
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The video lecture focuses on determining if a specific range of IP addresses constitutes a valid Classless Inter-Domain Routing (CIDR) block and finding its representation. The instructor presents a problem involving the range 100.1.2.32 to 100.1.2.47. He systematically applies three rules: contiguity, power-of-2 size, and divisibility of the first address. Through step-by-step calculation, he verifies the block size is 16, confirms it is a power of 2, and checks if the starting address is divisible by 16. Finally, he derives the CIDR notation /28. The lecture is structured around a specific question displayed on the slide, guiding the student through the verification process.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor introduces the problem statement displayed on screen: "Consider a block of IP Addresses ranging from 100.1.2.32 to 100.1.2.47." He underlines the question "Is it a CIDR block?" and lists the "Rules for Creating CIDR Block (Network)". He begins calculating the total number of addresses by subtracting the start from the end: "47 - 32". He emphasizes the need to add 1 for inclusive counting, writing "(47 - 32) + 1". He explains the "plus 1" concept using a small example "0-9" resulting in 10 numbers. He calculates the total size as 16. He writes "15 + 1" and circles "16". He also writes "35" and "35" vertically, seemingly checking something else or just scribbling, but focuses on the 16.

  2. 2:00 – 3:38 02:00-03:38

    The instructor verifies the calculated size of 16 against the rules. He checks if 16 is a power of 2, noting the sequence "8, 16, 32, 64, 128" written on the board. He then applies the third rule: "First IP Address of the block must be divisible by the size of the block." He writes "32 / 16" and confirms the result is 2, meaning it divides evenly. He concludes it is a valid CIDR block. He then determines the CIDR representation. Since the block size is 16 ($2^4$), he deduces the host bits are 4. He calculates the network prefix as $32 - 4 = 28$. He writes the final answer "100.1.2.32 / 28". He also draws a diagram of 32 bits to visualize the host bits.

The lesson effectively demonstrates the algorithmic approach to validating CIDR blocks. By breaking down the problem into size calculation, power-of-2 verification, and divisibility checks, the instructor provides a clear method for students to solve similar networking problems. The final derivation of the /28 prefix solidifies the connection between block size and CIDR notation. The visual aids, such as the list of powers of 2 and the divisibility check, reinforce the theoretical rules with practical application.

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