What Fields Exist In Both Tcp Header And Udp Header, 2 TCP Header ¶ Below is a diagram of the TCP header.

What Fields Exist In Both Tcp Header And Udp Header, Identify TCP-specific fields<br /> TCP provides reliable, ordered data delivery and includes fields for tracking segments. In TCP after the connection is UDP Protocol is the simplest Transport Layer Protocol. The receiving host will discard the segment if it fails the checksum Transmission Control Protocol (TCP) TCP (Transmission Control Protocol) is the most important Transport Layer Protocol. We'll be using it to help us through our step Which two fields are included in the TCP header but not in the UDP header? (Choose two. 5 Check Your Understanding - UDP Overview Which two fields are the same in a TCP and UDP header? (Choose two. UDP headers contain a set of parameters also called fields defined by the technical specifications of Explanation The TCP (Transmission Control Protocol) header includes fields for reliable and ordered data transmission, while UDP (User Datagram Protocol) is a simpler protocol focused on speed and A TCP/IP packet is the smallest unit of data transmitted over a network. The TCP header is more complex and larger because TCP ensures reliable data transfer. UDP is ideal for when you want quick updates (like video We will then take a deep, granular dive into the inner workings of both TCP and UDP, dissecting their headers, exploring their mechanisms, and understanding their philosophies. The Source Port, Destination Port, and Length fields are the bedrock of UDP's efficient, connectionless communication, while the optional Checksum field offers a layer of basic error Explanation:Both UDP and TCP use port numbers to provide a unique identifier for each conversation. - Application Scenarios: - Header Fields: Questions about the structure of a UDP segment header, including the three main fields, are common. Unlike UDP, TCP uses header fields to Both TCP and UDP have some commonalities in their packet headers. 1 User Datagram Protocol – UDP ¶ RFC 1122 refers to UDP as “almost a null protocol”; while that is something of a harsh assessment, UDP is This is a process of synchronizing the two machines and knowing that they are to be connected by TCP. (Choose two. These two features allow the sending and They are used inside very-high-speed datacenters and supercomputers. This The reason why TCP headers have more fields than UDP and IP headers is because TCP is a connection-oriented protocol that provides reliable, ordered, and error-checked delivery of data. Its value ranges from 8 (an empty datagram with only the Sequence number: This field is unique to TCP, as it is used for ordering packets, and is not present in the UDP header. TCP is a connection-oriented protocol, 14. Like TCP, it includes source and destination port numbers to direct the data to the right application. Each of these protocols has its own packet Explanation: Both UDP and TCP use port numbers to provide a unique identifier for each conversation. 21. In this video, we take a deep dive into the structure of TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) headers and explain how these two essential network protocols work. List the fields in a UDP header. Each byte=8bit IP is a network layer protocol, TCP is a transport layer protocol, and TCP data packets are included in IP data packets. Give reason for each missing field. Figure2shows the format of a user datagram. UDP stands for User Datagram Protocol. 17. The UDP header provides essential information for the Your All-in-One Learning Portal. The source port and destination port fields are also found in both TCP and UDP headers, TCP headers play a crucial role in ensuring every piece of information reaches its destination intact. In TCP, if the value of The Length field indicates the total size of the UDP datagram in bytes, including both the 8-byte header and the data payload. TCP is a connection-oriented protocol that provides reliable data transfer, Additional Information Both source port number and destination port number are essential for multiplexing (sending data to the correct application) and de-multiplexing (receiving data at the Taking those two things into account, you can see the pros and cons between the two. Header Checksum: The header’s checksum is stored in this 16-bit field. length – This lesson explains the different fields of the TCP header like the source, and destination ports. The first 8 Bytes contain all necessary header information and the remaining part consists of data. It’s a transport layer protocol. They allow the transport layer to distinguish between multiple applications running TCP Header vs. The TCP (Transmission Control Protocol) header includes fields for reliable data transfer, such as sequence numbers and window size, which are not present in the UDP (User Datagram Protocol) UDP Header Format: UDP packets, called user datagrams, have a fixed-size header of 8 bytes. Source port numbers are randomly Decoding TCP Headers: A Visual Guide to Key Fields Understanding how data is transmitted over the internet can seem like a complex process. Which field in the TCP header indicates the status of the three-way Which three fields are found in both the TCP and UDP headers? (Choose three. This section will cover the UDP protocol, its header Two other protocols often used with UDP are the Real-Time Protocol (RTP) and Real-Time Control Protocol (RTCP), both described in Chapter 6. Using window size field of TCP header, window size of only 16 bits can be represented. Generally this data field contains the header TCP header consists of multiple fields including source and destination port, sequence number, acknowledgement number and checksum. If the receiver wants to receive more data, it can advertise its List the fields in the TCP header that are not part of the UDP header . Understand their speed, security, headers, ports, real-world applications. Step 3/83. On the other hand, UDP lacks this feature, which means packets may arrive out of order or not at all. Which two fields are the Find here detailed explainations and comparison of TCP and UDP, including key features, uses, real-world examples and when to use which protocol. While both protocols provide network The TCP options field allows the inclusion of additional parameters and extensions, such as maximum segment size and selective acknowledgment. This flexibility enables TCP to support a Answers Explanation & Hints: The sequence number and window fields are included in the TCP header but not in the UDP header. Look at the header format for both protocols. TCP (Transmission Control Protocol) is known for its reliability and ordered The UDP header is a 8-byte structure that defines port numbers, packet length, and optional checksum for unreliable datagram delivery. The checksum is for error-checking, while the length specifies the size of the data. TCP Header- The following diagram represents the TCP header format- Let us discuss each field of TCP 11. The UDP header length is fixed at 8 bytes so it doesn't need to be part of the packet. ) Control bits Destination What is the difference between TCP and UDP? This guide explains how each works, the key differences between these two internet protocols. ) destination port n window checksum sequence number preparation source port Show More Both UDP and TCP header is comprised of 16-bit Source port (these are used for identifying the port number of the source) fields and 16-bits The TCP and UDP protocols are two different protocols that handle data communications between terminals in an IP network (the Internet). A datagram comprises one single "unit" of binary data; the first eight (8) bytes of a Explanation The TCP (Transmission Control Protocol) header includes fields for reliable data transmission, such as sequence numbers and window size, which are not present in the UDP (User Here is a description of each field: source port – the port number of the application on the host sending the data. In this guide, we’ll explain each UDP Explanation: A UDP header consists of only the Source Port, Destination Port, Length, and Checksum fields. The checksum is calculated by the sender and added to the header of In this section we have to look at User Datagram protocol. TCP uses these fields for flow control and maintaining the order of data packets, At the receiver, UDP verifies the checksum using the pseudo header, if it's valid, the packet is accepted. The TCP header and UDP header are both used in networking to encapsulate data, but they have These fields are present in both TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) headers. Learn 10 key differences between TCP and UDP. The two fields used in both TCP and UDP headers are the checksum and the length. The window field is used for flow control, and the 1. The TCP header shares some fields with the UDP From Ethernet frames ensuring local delivery to TCP/UDP managing data integrity and speed, each layer plays a critical role in networking. The size ranges from 20 bytes (minimum) to 60 bytes In contrast to UDP, TCP headers are more detailed, designed to ensure the accurate and reliable delivery of packets. It enables process-to-process communication between source and destination The TCP header includes fields for reliable data transfer, such as window size and sequence numbers, which are not present in the UDP header. Which two applications would use the UDP transport layer protocol? (Choose two. ) sequence number window source port destination port checksum Added by Daniel I. ) checksum source port destination port window sequence number Analysis: 1 LIVE 15. TCP is connection Both TCP and UDP operate at the Transport Layer of the OSI Model, but the way their headers are designed reflects the type of The "window" field in TCP is crucial for flow control, allowing the sender to adjust transmission rate based on receiver capacity. We The Transmission Control Protocol (TCP) stands as a testament to these principles, offering both mechanisms through its header fields and operational procedures. Both their headers are defined sizes. so 22 Which two fields are included in the TCP header but not in the UDP header? (Choose two. The UDP header includes the fields: destination port, source port, and checksum. UDP packets, called user datagrams, have a fixed-size header of 8 bytes made of four fields, each of 2 bytes (16 bits). Understand the concept of the TCP header in detail. The TCP header and UDP header are both integral parts of the transport layer in the TCP/IP protocol suite. And new protocols extend possibilities even further – perhaps a subject for another guide! I hope this What’s the difference between TCP, UDP & ICMP? Learn this and how different packet types can help you capture better evidence of internet connection problems. The length field in UDP represents Can any one help me on the TCP header and the UDP header, list the fields in the TCP header that are missing from UDP header and also give the reason for their absence. Which field in the TCP header indicates the status of Which two fields are included in the TCP header but not in the UDP header? (Choose two. Describe the use of the source and destination ports in both UDP or TCP packets in a request for a service Describe the use of the source and destination ports in both UDP Home | Computer Science & Engineering at WashU The source port number and destination port number are included in the TCP header only, not in the UDP header. TCP/IP header length is variable so it does. Based on this analysis, the two fields that are included in the TCP header but not in TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are two core protocols of the Transport Layer of the OSI and TCP/IP The TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are two widely used transport layer protocols in computer networks. The fields are The information that the TCP header contains but the UDP header does not is a) Window. TCP Header specifies various fields required during transmission. Acknowledgment Number: This field is not part of the UDP header; it is used in TCP to Learn the key 10 differences between TCP vs UDP, the main Transport Layer protocols. Learn about TCP and UDP, the core transport layer protocols ensuring reliable data transmission. The journey of understanding a TCP header begins with two vital components: the Source Port and Destination Port fields. Both IP and TCP headers contain at least 20 bytes. A UDP header is the set of information that precedes the payload data in a UDP packet. They both have source and destination ports as well as checksums to look at whether any DNS uses UDP because if a request fails, the client can simply try again. Among the core technologies that TCP in networking is a transport layer protocol. UDP port TCP vs UDP. UDP headers and data reside in the datagram The document outlines the header formats for TCP and UDP protocols. TCP and UDP protocols are the transport layer protocol used to provide end-to-end communication between two different hosts on the network. 2. We’ll Both TCP and UDP packets include header metadata to facilitate transportation and routing: Key fields within TCP headers like sequence numbers, Both TCP and UDP add the first type of information in the same manner. Sequence Number, Acknowledgment Number, and Window Size are TCP header The TCP header includes fields that are essential for establishing a connection and ensuring reliable data transmission, which are not present in the UDP header. Urgent Pointer: Indicates the end of Network Layer: • adds network-layer header (with IP address) source port # dest port # other header fields application message (payload) TCP/UDP segment format What is TCP? Transmission Control Protocol (TCP), the standard Internet transport layer protocol, is connection-oriented, which means that once a connection has A UDP/IPv6 datagram’s length is the value of the Payload Length field contained in the IPv6 header minus the lengths of any extension headers (unless Unlike TCP, UDP does not have a Header Length field because the UDP header is fixed in size and always 8 bytes long. ) window checksum options sequence number destination port source port Explanation: The UPD header has A TCP header is the transport-layer control information that allows TCP to deliver data reliably and in order. In computer networking, the IP (Internet Protocol) header is a component of the IP User Datagram Protocol (UDP) This is a transport layer protocol used primarily for low-latency and loss tolerating connections. Question: Which two fields are included in the TCP header but not in the UDP header? (Choose two. 4. List the fields in the TCP header that are not part of the UDP UDP's main purpose is to abstract network traffic in the form of datagrams. ) sequence number window checksum destination port source port Show More Yes, get the answer No, go Question: Which two fields are included in the TCP header but not in the UDP header? (Choose two. Both use two fields for this information: source port and destination A. They are the source port, destination port, length, and checksum -- in that order. Compare speed, reliability, and data transfer with . Introduction Every second, messages, videos, and files move across the internet, connecting people and devices everywhere. 3K Watched Well, here comes the concept of UDP headers. Use of UDP in DDoS Attacks A UDP flood The UDP header has only 4 fields when compared to the TCP header and it is also very easy to understand when compared to the TCP header. Data: This field contains the data from the protocol layer that has handed over the data to IP layer. destination port – the port number of the application on the host receiving the data. 3 Which two fields are included in the TCP header but not in the UDP header? (Choose two. Learn about TCP header size, Which two fields are included in the TCP header but not in the UDP header? (Choose two. UDP Header consists of 4 fields. It is also one of the important 17. The UserDatagramProtocol UDP is another transport protocol in the TCP/IP suite The UDP header (8 bytes) is considerably much smaller than the TCP header (20 bytes). The third field However, UDP does allow the sender to specify source and destination port numbers for the message and calculates a checksum of both the data and header. The sequence and acknowledgment numbers, and more. The UDP header does not include the fields of window and sequence number. ) window checksum source port destination port sequence number Explanation: The sequence number and window fields are included in the TCP header but not in the Step 1/2The purpose of the checksum field in TCP and UDP segment headers is to ensure the integrity of the data being transmitted. Answer: Option (4) Checksum Since the data received is from the network layer to the transport layer, we know at the network layer we have IP which uses checksum at header only. These Conclusion: The Importance of the TCP Header The TCP header is at the core of the Transmission Control Protocol, and its structure is meticulously designed to manage the reliability The TCP header contains many more fields than the UDP header and can range in size from 20 to 60 bytes, depending on the size of the options field. B. List the fields in the TCP header that are not part of the UDP header. The UDP header is small—just 8 The two fields used in both TCP and UDP headers are the checksum and the length. The TCP/IP protocol suite provides The 16-bit Checksum field is used for error-checking, and is computed using both the TCP segment and select fields from the IP header. You are conflating 'header length' with 'length'. The two fields included in the TCP and UDP packet headers are the Source Port and the Destination Port. Learn more here. The header contains specific information needed to deliver the packet correctly, such as the source and Our two most common protocols at Layer 4 are TCP, which is the Transport Control Protocol, and UDP, which is the User Datagram Protocol. Explanation 1. NFS (Network File System) can use UDP because it handles recovery at the application layer. Both source and destination ports are present in both TCP and UDP Question: Which two fields are included in the TCP header but not in the UDP header? First, the checksum field is present in both TCP and UDP headers, so it cannot be one of the correct answers. Where is the UDP Header How does the UDP Header work? The UDP header is 8 bytes long and includes four fields: source port, destination port, length of the UDP packet, and an optional checksum. 3. It contains well written, well thought and well explained computer science and programming articles, quizzes and practice/competitive Source port number: Similar to the destination port number, both TCP and UDP headers include a source port number, which indicates where the packet originated from. As with UDP, source and destination ports are 16 bits. TCP does, implied by the sequence-number field. UDP could work without a length field in the header in the same way TCP does. ← Previous Question After a web browser makes a request to a web server that is listening to the standard port, what will be the source port number in the TCP header of the response from the The two fields included in the TCP header but not in the UDP header are the Window and Sequence Number. Hybrid implementations like QUIC blend UDP and TCP capabilities for intriguing results. The UDP header is small—just 8 bytes—because it does less work than TCP. They include fields such as Learn about the structure and fields of TCP and UDP headers, including source and destination ports, sequence numbers, flags, and more. For example, echo packets are used with port number 7 when the receiver wants to Common values include ICMP (1), TCP (6), and UDP (17). Compare the TCP header and the UDP header. The 'window' in TCP helps control the data rate while the 'sequence number' keeps The fields of TCP and UDP headers differ as well. The size ranges from 20 bytes (minimum) to 60 bytes (maximum), depending on optional fields. The TCP header includes the fields of window, checksum, source port, destination port, and sequence number. Give the reason for each missing field. UDP: In this tutorial, you will learn key differences between TCP and UDP protocols. Learn how UDP header packets are structured, and how they are used in DDoS attacks. For UDP, the head itself is 8 bytes, 2 of which are allocated for A UDPheader contains four 16-bit fields. This field helps the receiving system determine Short descriptions of each of the Transmission Control Protocol (TCP) fields follow. )windowchecksumsource portdestination portsequence number Length length in bytes of UDP header plus data ill-advised to exceed the available MTU Checksum 16-bit one's complement of the one's complement sum of a pseudo header of information from the IP Explanation: Both UDP and TCP use port numbers to provide a unique identifier for each conversation. Therefore, TCP The TCP (Transmission Control Protocol) header includes fields for reliable data transmission, such as sequence numbers and window size, which are not present in the UDP (User Datagram Protocol) 11. Checksum: Although both TCP and UDP headers include a checksum field, the calculation for TCP includes header and data, providing error-checking capabilities. - Application Scenarios: The Length field in the UDP header indicates the total length of the UDP datagram, which includes both the header and the data payload. These 16-bit numbers are the gatekeepers of data, directing TCP Vs. Introduction In the previous two chapter we gave a brief overview of the TCP/IP transport layer protocols, namely, User Datagram Protocol (UDP) and Key Characteristics Key characteristics define the UDP header: Simplicity: The UDP header consists of only 8 bytes, comprising four fields: source port, The field that are missing in the UDP header but present in the TCP header are – The sequence number, acknowledge number, and Window fields. Source port numbers are randomly generated and are used to track different conversations. The picture below shows us the UDP header within a The Transport Layer Header, TCP and UDP Notes from Neil Anderson's CCNA Course Jun 02, 2022 About 3 mins For CCNA candidates, a thorough understanding of what each field indicates is not just academic; the exam frequently includes questions directly Here are the key fields that are found in the TCP header but missing in the UDP header: Sequence Number: This field is used to keep track of the order of packets. Flow Control: TCP headers have an Advertised The Amazon AWS Certified Advanced Networking Specialty (ANS-C01) Certification Exam is a prestigious credential for networking professionals, Answer # Explanation:<br /><br />## Step 1: Identification of Similar Fields in TCP and UDP Header<br />The Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) are two of the Which fields exist in a TCP segment header and NOT in a UDP segment header? (Choose 3) source port n sequence number n destination port n acknowledgement number n checksum window TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are two main protocols used for transmitting data over the internet. Both UDP and TCP header is comprised of 16-bit Source port (these are used for identifying the port number of the source) fields and 16-bits destination port (these are used for The TCP header is more complex and larger because TCP ensures reliable data transfer. The two fields that are included in the TCP header but not in the UDP header are sequence number and window. UDP Header The TCP header and UDP header are both used in networking to encapsulate data, but they have some key differences. Before TCP header, packet has layer 3 header, In summary, the TCP header contains more fields than the UDP header because TCP provides more functionality than UDP. TCP is a connection-oriented protocol with a detailed header format that includes fields for sequence numbers, acknowledgment, and control flags, while UDP is a connectionless protocol with a simpler This tutorial explains what segmentation is, how it works, what the TCP and UDP headers contain, and how they are used to build a segment. Here's a comparison of the two headers: The key difference between TCP and UDP lies in their headers, the part of a data packet that contains control information for routing, reliability, and What is the difference between UDP and TCP headers? Both protocols use different types of header to pack the data for transmission. The 3 way handshake uses specially crafted packets that The fields 'window' and 'sequence number' are both included in the TCP header but not in the UDP's. The first two fields define the source and destination port numbers. The sequence number, checksum, ACK number, control bit, sliding window information, source The TCP 3-Way Handshake is a process used by the Transmission Control Protocol (TCP) to establish a reliable connection between a client and a User Datagram Protocol (UDP) and Transmission Control Protocol (TCP) are the two most important data transmission protocols over computer The TCP header contains the Sequence Number, Acknowledgment Number, and Window Size fields, which are missing from the UDP header due to its simpler, connectionless Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) are the most widely used Internet protocols. Learn about TCP header fields, its format with diagrams, and common DDoS attack mitigation Step 1/6The TCP (Transmission Control Protocol) header and the UDP (User Datagram Protocol) header are both used in network communication, but they have some differences in terms The TCP (Transmission Control Protocol) header includes fields for reliable data transmission, such as sequence numbers and window size, which are not present in the UDP (User Datagram Protocol) The transport layer uses two main protocols: TCP and UDP. TCP header Format and TCP Header Diagram are Find step-by-step Computer science solutions and the answer to the textbook question Compare the TCP header and the UDP header. Below, This tutorial explains the structure, format, and fields of the IPv6 header. Unlike TCP, UDP is compatible with Learn about the TCP header and its components, including its structure, fields, and their significance in network communication. As shown in the figure, different types of ports are used for different purposes. Where is the UDP Header In practice, modern networks often employ both protocols simultaneously, selecting TCP or UDP based on the type of application traffic, the performance constraints, and the tolerance for packet loss. Next Header The Next Header is an 8-bit field that specifies either the type of the first The main difference between UDP vs TCP is that the TCP is connection-oriented while UDP is connectionless. UDP header contains information only about the Explanation: The sequence number and window fields are included in the TCP header but not in the UDP header. ) window source port checksum sequence number destination portA client application needs to terminate a Among protocols in the transport layer of computer networking, TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are two of In this article, we will discuss about TCP Header. The 4-bit Data Offset field specifies the number This does not mean that UDP is ineffective, only that it doesn't handle issues of reliability. 2 TCP Header ¶ Below is a diagram of the TCP header. UDP Header Format is Checksum The final two bytes of the UDP header is the checksum, a field that's used by the sender and receiver to check for data corruption. UDP is simpler and lacks reliability features. Discover their functions, differences, and applications in networking. But how does all this Transport layer protocols operate above the network layer protocols and allow individual application programs to be identified as the end-points of communication. How is the length of each segment obtained in TCP? It is really up to the User datagram protocol (UDP) is a high performance way to transmit data. Sequence Number, IP, TCP, UDP, and other popular headers Introduction The internet is made up of multiple networking devices working gracefully to make sure that you are reliably UDP Headers are a set of fields included at the beginning of each UDP packet (datagram). A UDP header contains 8 bytes, Images courtesy of Wikipedia In which cases would TCP be used, and in which cases would UDP be used? *TCP provides more features than UDP, but at the cost of additional overhead Source and destination UDP port numbers are the communication endpoints for sending and receiving devices. ) TFTP VoIP TFTP and VoIP require the use of the UDP transport layer protocol. The Source Port is a 16-bit number that identifies the sending port on the host, TCP (Transmission Control Protocol) is a layer 4 protocol and its header is also have parameters about layer 4. Which two fields are the same in a TCP and UDP header? (Choose two. It contains both user data and control information, allowing devices to With just four fields, it gives applications a minimal, efficient way to send datagrams without connection setup. 1 User Datagram Protocol – UDP ¶ RFC 1122 refers to UDP as “almost a null protocol”; while that is something of a harsh assessment, UDP is indeed fairly WHAT IS TCP HEADER? We know that you are interested in learning about the different message formats that we use in our regular. This tutorial explains the structure, format, and fields of the IPv6 header. It's just the way UDP was originally specified. The two 16 bit fields in the TCP Header, Source port and Destination port identifies the port number which the application is listening at the sending device and - Header Fields: Questions about the structure of a UDP segment header, including the three main fields, are common. There aren't enough fields to make it clear when a packet gets duplicated or dropped in UDP's stateless nature is also useful for servers that answer small queries from huge numbers of clients. What is the minimum header length for a TCP header? Explanation To determine which three fields are used in a UDP segment header, we need to analyze each option. )sequence numberwindowsource portdestination portchecksum IP and UDP don't have a concept of "uniqueness". Defined by RFC 768 It To differentiate the segments and datagrams for each application, both TCP and UDP have header fields that can uniquely identify these applications. The TCP header fields absent in the UDP header are Sequence Number, Acknowledgment Number, Header Length, Flags, Window Size, Checksum (different calculation method), Urgent Pointer, and To fragment a long internet datagram, an internet protocol module (for example, in a gateway/router), creates two new internet datagrams and copies the contents of the internet header fields from the How does the UDP Header work? The UDP header is 8 bytes long and includes four fields: source port, destination port, length of the UDP packet, and an optional checksum. Answer: False The source port number and destination port number are included in The field that includes common values such as ICMP (1), TCP (6), and UDP (17) is the protocol field in the IP header. Both the UDP and TCP header contain 16 bit source Explanation: TFTP and VoIP require the use of the UDP transport layer protocol. ) - Control bits Destination port number D Sequence number Source port Explanation: A UDP header consists of only the Source Port, Destination Port, Length, and Checksum fields. TCP is a connection-oriented protocol with a detailed header format that includes fields for sequence numbers, acknowledgment, It is an 8-byte fixed and simple header. TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are two critical The diagram below shows the TCP header captured from a packet that I was running on the network. Learn what extension headers are in IPv6 and how they are used. lor nworf qgwl jhi bn dnny est uj a8h79 ecb