This action is similar to an amplifier. Generally, layer 3 devices divide the broadcast domain but the broadcast domain can be divided by switches using the concept of VLAN. Students also viewed. (Select two) Hub Repeater Bridge Router Switch Gateway. Study with Quizlet and memorize flashcards containing terms like For a network technician one benefit of understanding the OSI seven-layer model is using it as a primary tool for:, Which of the following reside at the physical layer of the OSI model? (Select 2 answers), At which of the following layers of the OSI model TCP/UDP. A Hub works on the basis of broadcasting. Functions of Physical Layer. Each layer of the OSI Model handles a specific job and communicates with the layers above and below itself. It regenerates a weak signal and extends the network’s range. A network device used to regenerate or replicate a signal. IP (both IPv4 and IPv6) addresses are Network Layer addresses that are used in the Network Layer packet header. Physical Layer in OSI Model; Data Link Layer; Session Layer in OSI model. 2. A hub or a repeater operate at Layer 1; they regenerate a signal without. Repeaters work at the physical layer of the OSI model. Bridges are connection devices between networks that operate in the data link layer of the OSI model. The OSI Model: An Overview. Graphically, we depict these layers with Layer 1 at the bottom of the stack, as shown in Figure 2-2. tl;dr Many different devices can encounter multiple OSI levels. Teknoowl – 7 Layer OSI adalah sebuah model arsitektual jaringan yang dikembangkan oleh badan International Organization for Standardization (ISO) yang menyediakan kerangka logika terstruktur bagaimana proses komunikasi data berinteraksi melalui jaringan. It is divided into seven layers that work together to carry out specialised network functions, allowing for a more systematic approach to networking. In the world of computer networks and communication, the OSI model stands as a cornerstone for understanding how data is transmitted, received, and processed. •Device : NIC, Bridges, Switch OSI Layers. Layer 3 switch. Repeater b. For this reason, they can be considered Layer 1 devices. The. 5) Layer 5 of the OSI model. Bit Stretcher. Fungsi repeater adalah untuk. Repeater hubs also participate in collision detection, forwarding a jam signal to all ports if it detects a collision. The lowest layer of the OSI model is concerned with data communication in the form of electrical, optic, or electromagnetic signals physically transmitting information between. Physical. Contoh lain dari peralatan atau perangkat pada lapisan 1 ini adalah hub, repeater, dan network card. To pass data through the repeater in a usable fashion from one segment to the next, the packets and the Logical Link Control (LLC) protocols must be the same on the each segment. The TCP/IP model is a concise version of the OSI model. It is both an OSI layer 1 (physical layer) and layer 2 (data link layer) device, as it provides physical access to a networking medium and provides a low-level addressing system through the use of MAC addresses. It connects networks using the same protocol. IFT 166 Introduction to Internet Networking Lab 1 OSI Model & TCP/IP Model Note: If possible, try to complete this lab where you have to multiple computers on the same network OSI & TCP/IP Models OSI model comparison with TCP/IP model In column 2, indicate the proper name for each of the seven layers of the OSI model corresponding to layer number. Repeater: Repeater is an electronic device. Repeater: Repeater is used for regenerating the signal and then transmit, if the previously transmit signal is found weak. Repeaters work within the physical layer of the OSI model, that is, there is no end-to-end change in the physical protocol across the repeater, or repeater pair, even if a different physical layer may be used between. Pada physical layer terdapat perangkat keras dasar jaringan yang terdiri atas Repeater, Multiplexer, Hubs (Passive and Active), Oscilloscope dan Amplifier. Data Link. The first 3 bytes are used for vendor identification and the last 3 bytes must be assigned a unique value within the same OUI. A repeater is a physical layer device. View Answer: Answer: Option. Hardware including networking devices, antennas, cables, modem, and intermediate devices such as repeaters and hubs; 2. Repeaters work at the Physical layer of the OSI model by. a. Features of Repeaters. 5. -At this layer, data is called a "bit". Which of the following answers refer to the OSI layer 2 header data? (Select 2 answers) Source MAC address. How does a repeater operate in the Physical Layer of the OSI model? arrow_forward Explain the primary function of a network switch in an OSI model, and provide an example of a situation where it is commonly used. Perangkat tersebut sebagai penyambung atau concentrator, dan menguatkan sinyal di kabel UTP. The cable length between two repeaters is limited from 100 to 1200 m, depending on the bit rate used. 3c/d defines Ethernet hubs and repeaters that operate at the Physical Layer. The implementation of this layer is. 7 OSI Layer. So, L2TP is a layer 1 protocol in TCP/IP terms. regenerating the signal to extend the distance it can travel. 7 OSI Layer. Repeater – A repeater operates at the physical layer. What layer number is the Session layer of the OSI model? 5. . A router recognizes _____ layer addresses. In a conventional network switch, each data message is received at layer 1, then passed up the management chain of the networkExplanation: The host to host layer conforms the transport layer of the OSI model. it facilitates troubleshooting . By definition of a layer 1 device, a repeater is a non-intelligent device that has no knowledge of the information the signal contains and so. A repeater regenerates the received signals and then retransmits the regenerated (or conditioned) signals on other. Network hubs explained. It is a hardware device used to extend a local area network. Repeater. 10. Data Link. Submit Search. The model focuses on providing a visual. Terakhir, lapisan terbawah di osi layer, yakni physical. -Physical media can be copper wire, rf signals, fiber optic, etc. A gateway is a network node that forms a passage between two networks operating with different transmission protocols. Step 2 of 3. 153. Question: Since the internet pretty much unanimous agrees that a hub is operating on layer 1 I wonder what arguments can be made for it operating on layer 2. 3)These devices have absolutely no knowledge of the. Dahulu komunikasi data yang melibatkan komputer-komputer dari vendor yang berbeda-beda. Transport layer. It means that bridges have more functionality (in terms of connection) than Layer 1 devices, such as repeaters and hubs. The main thing that repeaters does is to REPEAT the signal from one side to other, it no taken on mind destination or something else, it just repeat the signal to the other ports. The correct answer is option 2. View the full answer Step 2. What is the name of a data unit used at the OSI physical layer? Frame Segment Bit Packet. It transmits data in the form of bits across the physical medium. The. In the physical layer, the bridge acts as a Repeater which regenerates the weak signals, while in the data-link layer, it checks the MAC(Media Access Control) address of the data. HUB mempunyai banyak port. CANopen applications can make use of CAN repeaters (OSI layer 1). Transciever works on the Physical Layer (Layer 1) of the OSI because its basically a repeater or a MAU Multi Station Access Unit. Repeaters are classified as Layer 1 devices in the OSI model, because they act only on the bit level and look at no other information. In the OSI model, Media Access Control (MAC) and Logical Link Control (LLC) sublayers are the components of: Data link layer. Layer 6 of the OSI model. As the explanation of one of them say: "Repeaters are protocol transparent". Q. Open Systems Interconnection Reference Model Learn with flashcards, games, and more — for free. _____ conversion is the representation of analog information by an analog signal. A layer of the TCP/IP model is both connection-oriented and connectionless. True. . A NIC needs a MAC address to communicate over the LAN. Definition: Physical layer is a layer 1 in the OSI model that plays major activity for interacting along with hardware components and signal mechanism system. At which layer of the OSI model is no header encapsulation applied? Repeater. False. As mentioned earlier in this chapter, repeaters work at Layer 1 (physical) by repeating the signal received from the transmitting side out to the receiver and vice versa. 7. A repeater works at the physical layer of OSI model and transparent to all protocols which are operating in the layer above the physical layer. This layer is the protocol layer that transfers data between adjacent network nodes in a wide area network (WAN) or between nodes on the same local area network (LAN) segment. Bridges and switches are layer 2 devices. The switch works on the data link layer of the OSI model, it is one type of multicast device which is used to connect the devices in the same network. Bit. The OSI model has seven. It is a hardware device used to extend a local area network. Protokol pada layer transport yang connection oriented dan reliable tapi delay transfer datanya tinggi adalah. 61. On cables, the electric pulse dissipates over distance, and in wifi, the signal gets weaker as it travels. Important Points. Where a repeater connects two cable segments of the same type, a media converter transitions from one cable type to another. So the PHY layer is on the transceiver, MAC layer on the NIC. It contains four layers, unlike the seven layers in the OSI model. E. The term that refers to a physical layer technique is called. ; The Physical layer is responsible for transmitting raw data bits. [1] The data link layer provides the functional and procedural. The main aim of using a repeater is to increase the networking distance by increasing the strength and. Jelaskan pengertian OSI? Jawab: OSI (open system interconnection) adalah model yang mendefenisikan standar untuk menghubungkan computer-computer dari vendor-vendor yang berbeda. One of the most important layers in the FOUNDATION Fieldbus model is the User Layer. The OSI Model can be seen as a universal language for computer networking. Untuk memahami cara kerja dari OSI Layer sendiri, anda dapat membayangkan dengan tahapan dalam mengirim surat. Modem. Some people use the terms concentrator when referring to a passive hub and multiport repeater when referring to an active hub. This layer manages the reception and transmission of the unstructured raw bit stream over a physical medium. Layer 2 switches forward data based on the destination MAC address (see below for definition), while layer 3 switches forward data based on the destination IP address. There are end-user devices such as workstations, printers and scanners. ) (A) Bridge (B) Router (C) Repeater (D) Switch (E) Hub. The bottom layer of the OSI Model is the Physical Layer. 2. The Network Interface Layer adds the source and destination Internet protocol (IP) addresses, and forwards the packets to the Internetwork Layer. Switch merupakan perangkat jaringan yang bekerja pada OSI Layer 2, Data Link Layer. 24 Sep 2021. Physical Layer. Bridge Repeater Bridge operates at the data link layer of the OSI Model. At this layer, the repeater receives the incoming signal and transmits it on the other side of the network segment. The physical layer is the lowest layer of the OSI model. The number of layers is. 2. The data link layer or layer 2 is the second layer of the seven-layer OSI model of computer networking. 5 terms. Functionality of the network remains unchanged by the use of repeater. In the OSI model, the physical layer PDU is known as: Bit. OSI is broken down into layers. Advantages of using the OSI layered model include, but are not limited to, the following: It divides the network communication process into smaller and simpler components, thus. The bottom layer of the OSI Model is the Physical Layer. Repeaters operate at the OSI Physical layer. Layer 1 network devices are dumb devices, meaning they make no intelligent decisions about handling data. A repeater is a connecting device that operates in the _____ layer of the Internet model. Repeater – A repeater operates at the physical layer. Repeaters remove the unwanted noise in an incoming signal. Signals that carry information within a network can travel a fixed distance before attenuation endangers the integrity of the data. ethernet repeaters, and network adapters. Study with Quizlet and memorize flashcards containing terms like _____ combine the characteristics of bridges and routers. A router isolates LANs in to subnets to manage and control network traffic. Layer 3 is the Network Layer where IP works and Layer 4 is the Transport Layer, where TCP and UDP function. Device B. The shapes and properties of the electrical. Each switch type may be used once, more. A network can contain many different types of devices. A _____ is normally a computer that operates in all five layers of the Internet model or seven layers of OSI model. A) network. Unformatted Attachment Preview. 2. . The Session layer is between the Transport and Presentation layers. Presentation layer of the OSI model. The role of modems is to modulate and demodulate (hence the word modem) data so that it can flow over the phone line, effectively transforming the data from digital to analog and viceversa. True or False? The Session layer is responsible for passing data to the Network layer at the lower bound and the Presentation layer at the upper bound. " [2] In the OSI reference model, the communications between systems are. It creates a direct interface via network applications such as a web browser (Google Chrome. Sinyal yang dihasilkan repeater memiliki kualitas. Repeaters operate in the third OSI layer with the first OSI layer. Identify the layer of the Open Systems Interconnection (OSI) model that. In the OSI model, a bridge operates at layer 2, or the data link layer. They merely amplify the signal, and are indeed at the Physical layer of the OSI model. 1. The boundary between the MAC layer and PHY layer for 100Mbit/s and above is the Media Independent Interface, for example the SFP socket. OSI Layer 2 – Data Link. In Star Topology, many popular Ethernet LAN protocols are used as CD(Collision Detection), CSMA (Carrier Sense Multiple Access), etc. 24 Sep 2021. r-_-mark • 1 yr. The minimum size of the OSI header is 5 bytes. Repeaters are also called Signal boosters. View solution. MAC atau Media Access Control di OSI Layer ada pada layer. B) data link. then explain how DHCP works in-top of IPv4 or 6 like DHCPv6 which uses Ipv6? that makes it at least a Sessoin or above layer. View this answer. A repeater works at the physical layer (Layer 1) of the OSI model and is transparent concerning the rest of the network infrastructure. The Data Link layer of the OSI model is where an access point (AP) operates. Use these for connecting different networks into an internetwork. UDP c. Spanning tree protocol is a link layer network protocol that ensures a loop-free topology for any bridged LAN. Repeaters: A repeater is a device that operates only in the physical layer. 7 Lapisan OSI Layer. The Open System Interconnection (OSI) atau biasa disebut juga OSI Layer secara umum dapat diartikan sebagai susunan atau kerangka jaringan yang membentuk sebuah model asitektur jaringan,. A: The physical layer is the first layer of the OSI model which deals with network cables or the… Q: Use VLSM to subnet the 128. They merely amplify the signal, and are indeed at the Physical layer of the OSI model. A router operates at layer(s) _____ of the OSI model. Each of these devices plays a different role within a network and each one functions at a particular. false. A repeater hub also participates in collision detection, forwarding a jam signal to all ports if it detects a collision . As against, Repeater do not understand any frames/packet/bits. How do repeaters and bridges operate within the OSI model, and what are their primary functions? How does a switch operate at the data link layer (Layer 2) of the OSI model, and what are its key functions? What is the primary function of a switch in the OSI model, and which layer does it operate on? How does the OSI model's protocol go from. This paper provides an overview of the Open Systems Interconnection (OSI) reference model which defines a hierarchical architecture that logically partitions the functions required to support system-to-system communication and has served as the most basic elements of computer networking since the. Application (Layer 7): The application layer is at the top of the stack – it’s the one most users see. In the OSI model, the physical layer PDU is known as: Bit. 3. Field Tech III - IV Conventional. Routers typically have two or more network port to which switches or hubs are connected to form an internetwork. Pada layer ini data diterima dari data link layer berupa Frame yang dan diubah menjadi Bitstream yang akan dikirim ketujuan berupa sinyal melalui media komunikasi. The OSI model, which stands for Open Systems Interconnection model, provides a structured framework for conceptualizing the different. only one transmission at a particular time. In the OSI model, the physical layer PDU is known as: bit. The application layer is the OSI layer closest to the end user; which means that both the OSI application layer and the user interact directly with the software application. User HUB dapat melakukan sharing dengan jaringan yang sama. To pass data through the repeater in a usable fashion from one segment to the next, the packets and the Logical Link Control (LLC) protocols must be the same on the each segmentA repeater that occurs as the first layer of the OSI layer is the physical layer. Repeaters are used to regenerate the signal. All other protocol layers that encapsulate data add just a header. A router operates at Layer 3, using the IP address to make forwarding decisions. This type of a hub is part of the media, its location in the Open System Interconnection (OSI) model is below the physical layer. Brouter are found in both the Data Link and Network Layer. A repeater works at the physical layer of OSI model and transparent to all protocols which are operating in the layer above the physical layer. Physical layer. 1. Repeaters are common in. D. ), How do switches and bridges learn where devices are located on a network?, At which OSI layer does a router operate to. Data link layer is a protocol layer that allows to keep manage the moving of data into and out of a physical link in a computer network. The layers are: Layer 1—Physical; Layer 2—Data Link; Layer 3—Network; Layer 4—Transport; Layer 5—Session; Layer. a. , IP). Media converters also work at the Physical layer of the OSI model. 1983. A network repeater works in the physical layer of the OSI model. Apa yang dilakukan oleh 7 layer OSI ? Ketika data ditransfer melalui jaringan, sebelumnya data tersebut harus melewati ke-tujuh layer dari satu terminal, mulai dari layer aplikasi sampai physical layer, kemudian di sisi penerima, data tersebut melewati layer physical sampai aplikasi. False. CANopen applications can make use of CAN repeaters (OSI layer 1). On which layer of. Network Layer: c. Switch mengenal MAC Adressing shingga bisa memilah paket data mana yang akan di teruskan ke mana. e. It works at the physical layer of the OSI model. The implementation of this layer is often termed PHY. Study with Quizlet and memorize flashcards containing terms like Which of the following reside at the physical layer of the OSI model? (Select 3 answers) IP address Network switch Hub Router Network cabling Ethernet frame Repeater, Physical layer of the OSI model is also known as: Layer 2 Layer 7 Layer 1 Layer 4, What are the characteristic. Manufacturing Company: Motorola, Microtel etc. 2 (Ethernet standard) ISO 2110 ISDNLocated at the lowest layer of the Open Systems Interconnection (OSI) communications model, the physical layer's function is to transport data using electrical, mechanical or procedural interfaces. Study with Quizlet and memorize flashcards containing terms like For a network technician one benefit of understanding the OSI seven-layer model is using it as a primary tool for:, Which of the following reside at the physical layer of the OSI model? (Select 2 answers), At which of the following layers of the OSI model TCP/UDP. They have faster-switching speed than the layer-2 switches. IFT 166 Introduction to Internet Networking Lab 1 OSI Model & TCP/IP Model Note: If possible, try to complete this lab where you have to multiple computers on the same network OSI & TCP/IP Models OSI model comparison with TCP/IP model • In column 2, indicate the proper name for each of the seven layers of the. On which layer of OSI does repeater works? physical layer Repeater – A repeater operates at the physical layer. It sends the signals for the unsteady areas to enlarge the system signals. 7. e. Repeaters are used to extend wire length or to regenerate attenuated signals. Bridges with more than two ports (multiport bridges) perform switching functions. Study with Quizlet and memorize flashcards containing terms like Routers operate on which of the following layers of the OSI Model? Layer 2 Layer 3 Layer 4 None of the above Layer 1, Which of the following ports is used for SMTP? 80 53 110 25, At which of the following OSI layers does the hub operate? Network Transport Physical Data link and more. A repeater regenerates the received signals and then retransmits the regenerated (or conditioned) signals on other segments. ), How do switches and bridges learn where devices are located on a network?, At which OSI layer does a router operate to. In this article, we will take a look. The Open Systems Interconnection (OSI) model defines a networking framework to implement protocols in layers, with control passed from one layer to the next. OSI 7-Layer Model LOGO Layer 1 Network component Repeater Multiplexer Hubs(Passive and Active) TDR Oscilloscope Amplifier Protocols IEEE 802 (Ethernet standard) IEEE 802. Model OSI (Open System Interconnection) diciptakan oleh International Organization for Standardization (ISO) yang menyediakan kerangka logika terstruktur bagaimana proses komunikasi data berinteraksi melalui jaringan. TCP/IP was designed and developed by the Department of Defense (DoD) in the 1960s and is based on standard protocols. Setiap layer hars memiiliki fungsi tertentu 3. Repeater takes high input power and provides low output power. I just checked both the Network+ and the Network+ OSI model practice tests and both have a question that places the repeater at the Physical layer. Salah satu contohnya dengan repeater bisa menghubungkan dua buah segmen kabel Ethernet 10BASE2. A bridge is a repeater with the added functionality of filtering content by. Method: Following should be done to understand this practical. • It transmits the data form of Bits or Signal. 1. Match each type of switch on the left with its corresponding characteristics on the right. A repeater operates at the physical layer. Study with Quizlet and memorize flashcards containing terms like Which of the following hardware devices regenerate a signal out of all connected ports without examining the frame or packet contents? (Select two. Contoh lain dari peralatan atau perangkat pada lapisan 1 ini adalah hub, repeater, dan network card. An Ethernet switch operates at the data link layer (layer 2) of the OSI model to create a. At which OSI layer does a router operate to forward network messages? - Data Link - Network - Session - Transport - Physical. The 7 Layers of OSI Model Explained. The data link layer or layer 2 is the second layer of the seven-layer OSI model of computer networking. Which layer of the OSI model is responsible for converting the packet to an electrical signal that will be placed on the wire? Group of answer choices. C) physical. It receives a signal and retransmits it at a higher level or higher power. The standard networking model for most computer networks. 62. In the OSI layer, repeater work at the first physical layer. Repeaters do not necessitate any additional. It receives a signal from one port, amplifies it, and retransmits the signal through the other port. The Transport Layer is the 4th layer of the OSI model. The second layer of the OSI model concerns data transmission between the nodes within a network and manages the connections between physically connected devices such as switches. It strengthens the weakened signal and extends the network’s range. Study with Quizlet and memorize flashcards containing terms like Which of the following hardware devices regenerate a signal out of all connected ports without examining the frame or packet contents? (Select two. OSI layer 4 (tcp/up), some filter through layer 7. It's employed to replicate the signal or information. It defines the characteristics of the interface between the devices and the transmission medium. C. Layer-3 switches are sometimes called routing switches or multilayer switches. Hub is a hardware device used at the physical layer to connect multiple devices in the network. A hub serves as a central point to which all of the hosts in a network connect to. e. A: A. A hub or a repeater operate at Layer 1; they regenerate a signal without looking at Layer 2 or Layer 3 information. The node that receives the message from the previous computer will retransmit to the next node. IFT 166 Introduction to Internet Networking Lab 1 OSI Model & TCP/IP Model Note: If possible, try to complete this lab where you have to multiple computers on the same network OSI & TCP/IP Models OSI model comparison with TCP/IP model • In column 2, indicate the proper name for each of the seven layers of the. Routers are the most complex devices, Hubs and switches connect computers to the LAN; routers connect LANs to one another. The performance of Local Area Networks (LANs) and Wide Area Networks (WANs) repeaters are used. Routers are found in the Network Layer. Physical Layer (Cable, Hubs, Repeaters) OSI layer 2. Session C. . Filters traffic by port number. On the other hand, Layer-2 switches forward data to the subsequent layer based on the system’s MAC address. Layer 1: The physical layer. ago. It is based on an algorithm invented by Radia Perlman while working for Digital Equipment Corporation. A gateway operates at layer(s) _____ of the OSI model. All of the other layers perform useful functions to create messages to. Expert-verified. Unlike a switch, a hub cannot filter the data, i. Repeater… Q: QUESTION 12 Compare between Repeaters and Bridges in term of. . 60. Physical. We know Networking Architecture has a 7-layer OSI model, where repeaters and devices come at the physical layer. At which layer of the OSI model is no header encapsulation applied? Repeater. A repeater operates at layer(s) _____ of the OSI model. It is also known as a signal booster, and it helps in extending the coverage area of networks. Repeater. Repeater operates in which layer of the OSI model? a. The application layer is the OSI layer closest to the end user, which. Q. D. So the PHY layer is on the transceiver, MAC layer on the NIC. Bridge connects two different LANs. 6. network layer of the OSI (open systems interconnection) model. The IEEE regulates the MAC addresses. It is based on the concept of splitting up a communication system into seven abstract layers, each one stacked upon the last. 4) Network layer of the OSI model. IFT 259 Introduction to Internet Networking Lab 1 (2%) OSI Model & TCP/IP Model Note: If possible, try to complete this lab where you have to multiple computers on the same network OSI & TCP/IP Models OSI model comparison with TCP/IP model In column 2, indicate the proper name for each of the seven layers of the OSI model corresponding to layer number. Layer 4 of the OSI model. Cara Kerja Repeater. Repeaters enables more CAN nodes in one CANopen segment or longer network length due to the refreshing of the bus signals. 3) Layer 3 of the OSI model. December 1, 2021. They are used for long-distance transmission or received on the other side. B. Repeater operates only on the physical layer i. 5. In vague, general terms, each layer is handled independently and assumes that the layers below/above it are functioning properly. Routers operate at: (Select two answers) 1) Physical layer of the OSI model. A repeater operates at the physical layer of the OSI model, which is responsible for the transmission and reception of raw bit streams over a physical medium. Study with Quizlet and memorize flashcards containing terms like The Open Systems Interconnection (OSI) model consists of: 1) 7 layers 2) 3 layers 3) 9 layers 4) 5 layers, Physical layer of the OSI model is also referred to as: 1) Layer 2 2) Layer 7 3) Layer 1 4) Layer 4, Which of the following protocols reside(s) at the application layer of the OSI model? We would like to show you a description here but the site won’t allow us. Physical Layer: b. Modem c. Layer 1 of the OSI Reference Model is where we define the “physical” elements of a digital data network. Layer 1: The Physical Layer. 5. Transport layer. Bridges are used to segment networks that have grown to a point where data traffic. Some switches can do both. A bridge is a network device that connects two or more LANs (local area networks) to form a larger LAN. Layer 6 of the OSI model. It helps in Transmission Medium decision (direction of data transfer). At which of the following layers of the OSI model is the problem MOST likely located? A. A. HUB termasuk dalam Layer 1 dalam OSI model (physical layer). The OSI Model layers are more for thinking about things.