What is duplex printing ?

                                    What is duplex printing ?

Duplex printing is a feature of some computer printers and multi-function printers (MFPs) that allows the printing of a sheet of paper on both sides automatically. Print devices without this capability can only print on a single side of paper, sometimes called single-sided printing or simplex printing.

Duplex print devices, depending on options, software, and printer settings, can print single-sided page to single-sided page (1:1) or double-sided page to double-sided page (2:2). Many can also combine single-sided pages into a double-sided page format (1:2). Double-sided booklet formats (2:2 with a center fold) are also available, depending on optional outputs from the printer.

Duplexed documents can be printed to be bound on either the short edge or the long edge. This functionality is mostly available on printers that come with a duplexer.^[1] Long edge binding in portrait mode allows pages to be turned side-to-side like a book. Short-edge binding allows the pages to be oriented correctly if they are flipped vertically, as in a notepad. This second form of printing/binding is sometimes known as "tumble." If the printing is done in landscape mode, these concepts are transposed since the print direction is different.

Single-sided printers can print both sides of the paper by manually removing and turning over a stack of sheets after one side is printed; however, the user has to manually turn the print job over and re-initialize the printing of the document, with care to ensure that the order and orientation is correct.

Duplex

Duplex

It is important that you understand duplex logic and how it affects traffic on a network. The communication mode of a device may either be half-duplex or full-duplex, depending on the connection type.

Half-duplex allows for one-way communication, which means that a device can only send or receive a data transmission at any given time. This option does not allow for simultaneously sending and receiving data. As part of a shared collision domain, hubs are inherently set up for half-duplex. Bandwidth suffers because a collision detection technology such as the CSMA/CD algorithm must be implemented. Collision detection can chew up 50–60% of the bandwidth on that ethernet LAN.

Full-duplex allows for two-way communication, which means that a device can simultaneously send and receive data transmissions. Full-duplex is available with dedicated switch port connections to a single device. If a switch port connection is configured for full-duplex, the CSMA/CD algorithm must be disabled. An ethernet connection set for full-duplex allows for 100% transmission speeds in both directions. For example, a 100Mbps connection can transmit data simultaneously at 100Mbps in each direction.

With ethernet, if a switch port and NIC offer multiple speed options as well as half- and full-duplex settings, autonegotiation can be configured on both devices. The switch and NIC automatically negotiate the connection speed and duplex so that the settings on both ends match. You may have heard of a 10/half or 100/full connection before. The term 10/half refers to a 10Mbps half-duplex connection. It is more likely that you will see 100/full, which indicates a 100Mbps full-duplex connection.

Top Questions and Answers on OSI Model

• List the layers of OSI?

From top to bottom, OSI layers are,

Application, Presentation, Session, Transport, Network, Data Link and Physical.

• What are the responsibilities of Data Link Layer?

Framing, Error detection, CRC and Physical Addressing is the task of DLL.

• What are the responsibilities of Network Layer?

Routing, IP Addressing and Path determination are the main responsibilities of Network Layer.

• What are the responsibilities of Transport Layer?

Transport Layer has a lot of function. Most important being,

1. Multiplexing and De-Multiplexing
2. Segmentation and Re-assembly
3. Flow Control
4. Error Correction
5. Connection Establishment
6. Sequencing
7. Acknowledgement
8. 3 way Handshake

• Routers work at which OSI layer?

Network Layer

• Switches work at which OSI layer?

Layer 2 and Some Switches can operate at Layer 3 and above

• What is a Window in networking terms?

Window is the amount of segments sent by TCP between two acknowledgements.

• What is the role of the LLC sublayer in datalink layer?

Logical Link Control provides error detection, using Ethernet trailer field frame check sequence (FCS).

• What is the function of the Application Layer in networking?

Application Layer is responsible for providing a user interface in between user and Network with the help of applications like web browsers.

• What is the difference between TCP and UDP?

Following are differences in TCP and UDP,

• TCP stands for “Transmission Control Protocol” UDP stands for “User datagram Protocol”.
• TCP is connection oriented protocol while UDP is connectionless protocol.
• TCP is more reliable than UDP.
• UDP is faster for data sending than TCP.
• UDP makes error checking but no reporting but TCP checks for errors and performs reporting.
• TCP provides guaranteed Delivery of Data but UDP has no guarantee.
• Header size of TCP is 20 bytes while that of UDP is 8 bytes.
• TCP has acknowledgement segments but UDP has no acknowledgement.
• TCP is used for application that require high reliability but less time critical whereas UDP is used for application that are time sensitive but require less reliability.

• What is the port no of DNS and Telnet?

DNS = 53, Telnet = 23

• Which service use both TCP and UDP ?

DNS uses both TCP and UDP

• What is the port no of SMTP and POP3?

POP3 = 110; SMTP = 25

• In which layer term “Frames” is used ?

Frames are PDU of Data Link Layer

• In which layer term “Packets” is used ?

Packets are PDU of Network Layer

• In which layer term “Segments” is used ?

Segments are used at Transport Layer

• Give some example for protocols work at Application layer ?

Application Layer Protocols are  HTTP, HTTPs, Telnet, SSH, DNS, FTP, TFTP, DHCP, RIP

• What is CRC? Which layer CRC works ?

Cyclic Redundancy Check is used to detect the errors in network. It works at Data Link Layer (LLC Sub Layer).

• What is the purpose of the Data Link?

Data Link Layer is responsible for Framing, Error Detection and Physical Addressing

• Which one is reliable – TCP or UDP ?

TCP is reliable.

• What is the port number of ftp (data) and ftp?

FTP port number 20 (Data); 21 for Control

• Which layer provides logical addressing that routers will use for path determination ?

Network Layer

• Which layer specifies voltage, wire speed, and pinout cables and moves bits between devices ?

Physical

• Which layer combines bits into bytes and bytes into frames, uses MAC addressing, and provide error detection ?

Data Link Layer

• Which layer is responsible for keeping the data from different applications separate on the network ?

Session layer.

• Which layer segments and resembles data into a data stream ?

Transport layer.

• Which layer provides the physical transmission sof the data and handless error notification, network topology, and flow control ?

Data Link Layer

• Which Layer manages device addressing, tracks the location of devices on the network, and determine the best way to move data ?

Network layer.

• How Data breaks down on each layer from top to bottom ?

Encapsulation occurs in following format

• MAC address works on which layer ? What are the differences of MAC sublayer and LLC sublayer?

MAC works at DATA LINK LAYER. Media Access Control provides physical addressing while Logical Link Control provides error detection, using Ethernet trailer field frame check sequence (FCS). It is 4 bytes field. When a sending device sends a data it put the data in a mathematical algorithm and it gets a product, sending device puts the product in FCS. When a receiving device receive a data it also put the data in same mathematical algorithm and get a product. If both products are same, Frame is accepted or else discarded.

• Which layer is responsible for converting data packets from the Data Link layer into electrical signals ?

Physical Layer

• At which layer is routing implemented, enabling connections and path selection between two end systems. ?

Network Layer

• Which layer defines how data is formatted, presented, encoded,and converted for use on the network ?

Presentation Layer

• Which layer is responsible for creating, managing and terminating sessions between applications ?

Session Layer

• DNS uses which protocol? Why?

DNS uses both TCP and UDP

• Which layer is closer to the user?

From sender point of view, Application Layer is closest and from Receiver point of view Pgysical Layer is closest.

• Differentiate between forward lookup and reverse lookup in DNS?

Forward Lookup: Name to IP resolution

Reverse Lookup: IP to Name resolution;

• What is IPSec?

IPSec provides data security at the IP Packet Level.

• What is the way to establish a TCP connection?

TCP Connection is established using three-way Handshake.

• What is the difference between flow control and error control?

Error Controls the process of detecting and correcting both the bit and packet level error. While flow control is a mechanism to ensure the efficient delivery of Data. Flow control is agreeing on the minimum amount of data that a receiver can handle at a time.

Questions on OSI Model with answers-

             Questions on OSI Model with answers-

OSI Reference Model

Q1- What does the acronym OSI stand for ?
Ans- Open System Interconnection. The OSI reference model is used as a guide for teaching and understanding the way networks operate.

Q2- What are the layers of the OSI model?
Ans- Application, Presentation, Session, Transport, Network, DataLink, Physical. An easy way to remember the order of the layers is: A-ll  P-eople  S-eem  T-o  N-eed D-ata  P-rocessing .

Q3- At which layer of the OSI model is a path decision made based upon an IP address ?
Ans- Network. At the network layer, data is transported in the form of a packet.

Q4- Which of the following takes place at the presentation layer ?
Ans- Encryption. The presentation layer encrypts data to be sent across the network, and decrypts it so that it can be accessed by the application layer on the receiving end.

Q5- Which is NOT a function of the Application layer ?
Ans- Windowing. Quality of Service and user authentication are also handled by the application layer.

Q6- Which layer of the OSI model contains the LLC sublayer and the MAC sublayer ?
Ans- Data Link Layer. The LLC and MAC sublayers allow for different layer 2 protocols to be used, such as Ethernet, Token Ring and FDDI.

Q7- How can data be transported in different layers ?
Ans- Data is transported in bits at the Physical layer . A bit is simply a binary digit. Either a 0 or a 1 . Data is transported in segments at the Data Link layer . At the data link layer, user data is encapsulated in a frame.

Q8- What is the function of Network Layer ?
Ans- The network layer establishes the route between the sender and receiver across switching points, which are typically routers. The most ubiquitous example of this layer is the IP protocol in TCP/IP. IPX, SNA and AppleTalk are other examples of routable protocols, which means that they include a network address and a station address in their addressing system. This layer is also the switching function of the dial-up telephone system. If all stations are contained within a single network segment, then the routing capability in this layer is not required.

Q9- The link for a switch connection is isolated from other data traffic except for what type of messages?
Ans- Following are the types of messages-
i. Multicast Messages – Message are sent to a specific group of hosts on the network.
ii. Broadcast Messages – Message is sent to all devices connected to the LAN.

Q10- Why are the layers of the OSI model important to the network administrator?
Ans- The Layers of OSI Model are important for the network administrator in the following manner-
i. To troubleshoot network problems by verifying functionality of each layer.
ii. In many cases it requires the network administrator to isolate at what layer the network problem   occurs.

OSI model FOR CCC EXAM

                        OSI model FOR CCC EXAM 

1. OSI stands for

a) open system interconnection
b) operating system interface
c) optical service implementation
d) none of the mentioned

Answer: a

2. The OSI model has _______ layers.
a) 4
b) 5
c) 6
d) 7

Answer: d

3. TCP/IP model does not have ______ layer but OSI model have this layer.
a) session layer
b) presentation layer
c) application layer
d) both (a) and (b)

Answer: d

4. Which layer links the network support layers and user support layers
a) session layer
b) data link layer
c) transport layer
d) network layer

Answer: c
Explanation: Physical, data link and network layers are network support layers and session, presentation and application layers are user support layers.

5. Which address is used in an internet employing the TCP/IP protocols?
a) physical address and logical address
b) port address
c) specific address
d) all of the mentioned

Answer: d

6. TCP/IP model was developed _____ the OSI model.
a) prior to
b) after
c) simultaneous to
d) none of the mentioned

Answer: a

7. Which layer is responsible for process to process delivery?
a) network layer
b) transport layer
c) session layer
d) data link layer

Answer: b

8. Which address identifies a process on a host?
a) physical address
b) logical address
c) port address
d) specific address

Answer: c

9. Which layer provides the services to user?
a) application layer
b) session layer
c) presentation layer
d) none of the mentioned

10. Transmission data rate is decided by
a) network layer
b) physical layer
c) data link layer
d) transport layer

.