TCP Header-Urgent Pointer Field

Duration: 4 min

This video lesson is available to enrolled students.

Return to /learn/COCUBES-PREPARATION/computer-networks/transport-layer-services/tcp-header-fields/asset-tcp-header-urgent-pointer-field after enrolling

Inside: a video lesson and guided study material.

Module outline

  1. Quantitative Aptitude: Number System, Divisibility Rules, HCF LCM, Percentage, Ratio and Proportion (Ratios), Average, Profit and Loss, Simple Interest and Compound Interest, Mixture and Alligation, Partnership, Age Problems, Time and Work, Pipe and Cistern, Speed Time and Distance, Algebra, Arithmetic, Data Interpretation, Sequence and Series (Series), Logarithm, Powers and Exponents (Surds and Indices), Permutation and Combination, Probability, Speed Mathematics and Basic Mathematics, Trigonometry
  2. Logical Reasoning: Coding Decoding, Blood Relations, Directions (Direction Test), Ranking, Order and Sequence, Seating Arrangements, Puzzle Solving (Puzzles), Data Arrangement, Syllogisms, Inequality, Data Sufficiency, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Series (Number and Letter Series) (Numerical Relations and Reasoning), Venn Diagram, Logical Sequence Of Words, Calendar, Clock, Cubes & Dices, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning)
  3. Verbal Ability: Noun, Pronoun, Adjectives, Verb, Adverb, Tenses, Subject Verb Agreement (Verb Noun Agreement), Articles, Preposition, Conjunction, Modals, Determiner, Vocabulary, Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Cloze Test (Cloze Passage), Sentence Correction (Error Correction), Sentence Completion (Fill in the blanks), Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Active Passive Voice (Voice), Direct and Indirect Speech, Sentence Construction
  4. Data Structures (Domain Test): Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  5. Algorithms (Domain Test):
  6. OOPs (Domain Test): Object Oriented Programming (OOPS)
  7. DBMS (Domain Test): Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, File Organization & Indexing, Relational Algebra, Relational Calculus, Transaction Management, Concurrency Control, Database Recovery, ORDBMS, Database Security & Authorization, Query Processing & Optimization, Enhanced Data Models, Data Warehousing & Mining, Big Data Systems, NoSQL
  8. SQL (Domain Test): SQL
  9. Operating Systems (Domain Test): Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling, File Management, Windows OS, Linux OS, Security, Distributed Systems, Virtual Machines
  10. Computer Networks (Domain Test): 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, Hardware basics, Network Security, Cloud Computing and IoT, Cyber and Info Security
  11. Coding: Coding Questions by Yash Sir, C Programming by Yash Sir, Programming in C++, Java, Python for Placements by Yash Sir
  12. Written English Test: English Writing Ability
  13. Psychometric Test: Behavioral Assessment (Behavioral Competency Profiling) (Psychometric Test)
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This short lecture segment focuses exclusively on the Urgent Pointer field within a TCP header. The instructor presents a slide defining the 16-bit urgent pointer as valid only when the urgent flag is set, used to indicate the position of urgent data. A hand-drawn diagram illustrates how the sequence number and urgent pointer combine to locate the last urgent byte in the data section. The instructor repeatedly points to the urgent pointer field in a TCP header layout, emphasizing that it is an offset added to the sequence number rather than an absolute address. The on-screen text consistently states: 'This 16-bit field, which is valid only if the urgent flag is set, is used when the segment contains urgent data. It defines the number that must be added to the sequence number to obtain the number of the last urgent byte in the…' The header diagram labels fields including source port address, destination port address, sequence number (32 bits), acknowledgment number, window size, and urgent pointer (16 bits). No worked numerical example is shown; the teaching relies on visual annotation and field identification.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor introduces the Urgent Pointer field, displaying on-screen text: 'This 16-bit field, which is valid only if the urgent flag is set, is used when the segment contains urgent data.' A hand-drawn diagram with an 'S' and arrow pointing to the data section illustrates how sequence number plus urgent pointer locates the last urgent byte. The TCP header structure at the bottom highlights the Urgent Pointer field alongside source port address, destination port address, sequence number, acknowledgment number, and window size. The instructor uses a pen to annotate the diagram and point at specific fields.

  2. 2:00 – 3:32 02:00-03:32

    The instructor continues pointing to the 'Urgent pointer' field in the TCP header diagram, emphasizing its 16-bit size and relationship to the 32-bit sequence number. On-screen text reiterates: 'It defines the number that must be added to the sequence number to obtain the number of the last urgent byte in the…' The instructor gestures toward the data section and points to the 'Urgent' flag in the header flags row, clarifying that the urgent pointer is a relative offset rather than an absolute address. The slide displays 'Urgent pointer 16 bits' and 'Sequence number 32 bits' as labeled field breakdowns.

The core concept is that the TCP Urgent Pointer is a 16-bit offset field, not an absolute byte address. It is only meaningful when the URG flag in the TCP header is set to 1. The field value is added to the segment's sequence number to compute the sequence number of the last urgent byte in the data payload. The instructor reinforces this through repeated pointing to the field in a header layout diagram and a hand-drawn schematic showing sequence number plus urgent pointer pointing into the data section. Key distinctions: (1) validity is conditional on the urgent flag; (2) it is an offset, not a direct position; (3) it identifies the last urgent byte, not the first. No numerical worked example is provided in the sampled frames; the lesson relies on structural identification and conceptual clarification. Students should remember: Urgent Pointer + Sequence Number = sequence number of last urgent byte, and the field is ignored if URG=0.

Loading lesson…