TCP Header Options
=====================

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        **What are TCP Header Options?**

        TCP header options are optional fields that extend the capabilities of the standard TCP header. They allow for features like performance tuning, enhanced security, and better congestion control.

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        **Why are TCP Header Options useful?**

        They enable advanced functionality beyond the basic header fields, such as window scaling, selective acknowledgments (SACK), and timestamping — improving efficiency and reliability of TCP communication.

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        **How do TCP Header Options work?**

        TCP options are included after the standard 20-byte TCP header. Each option has a kind field, length, and value. These options are negotiated during the TCP handshake or included in data segments.

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        **Where are TCP Header Options used?**

        They are used in networks requiring advanced features like high throughput, long-distance communication, or improved error handling — such as data centers, cloud environments, and WANs.

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        **Which OSI layer do TCP Header Options belong to?**

        TCP header options operate at the **Transport Layer (Layer 4)** of the OSI model, as part of the TCP segment structure.

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        **Are TCP Header Options Windows specific?**

        No, TCP options are part of the TCP/IP standard and are supported on all major platforms including Windows, Linux, and macOS.

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        **Are TCP Header Options Linux specific?**

        No, Linux supports TCP options just like other platforms. Tools like `sysctl` and `iptables` allow configuration of some TCP options.

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        **Which transport protocol uses TCP Header Options?**

        Only **TCP** uses TCP header options. Other protocols like UDP do not have optional header fields.

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        **Are TCP Header Options used in the client-server model?**

        Yes, during the client-server connection establishment phase (3-way handshake), TCP options can be negotiated to enhance performance and reliability.


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        Topics in this section,

                * :ref:`Learnings in this section <Header_Options_step1>`

                * :ref:`Terminology <Header_Options_step2>`

                * :ref:`Version Info <Header_Options_step3>`

                * :ref:`TCP Header Options Basic Setup on Ubuntu using IPv4 <Header_Options_step18>`

                * :ref:`Reference links <Header_Options_step17>`

.. _Header_Options_step1:

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    .. tab-item:: Learnings in this section

        * In this section, you are going to learn

.. _Header_Options_step2:

.. tab-set::

    .. tab-item:: Terminology
        
       * Terminology


.. _Header_Options_step3:

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    .. tab-item:: Version Info
    
         * Version Info


.. _Header_Options_step18:

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   .. tab-item:: TCP Header Options Basic Setup on Ubuntu using IPv4
       
      * setup


.. _Header_Options_step17:

.. tab-set::

    .. tab-item:: Reference links
     
       * Reference links