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Option: A
Explanation :While the Sikorsky name is forever linked to helicopters, Igor Sikorsky (1889-1972) was a versatile aviation designer and developer whose 50-year career included pioneering work on fixed wing aircraft and flying boats, all before returning to his first love, helicopters, and creating the first practical one.
By 1939, Sikorsky’s VS-300 was ready to make its first flight. “It was the first practical, workable helicopter that could do everything it was supposed to do, fly, hover and deal with all the different aspects that people were trying to solve with torque and lift,” Cochrane says.
The VS-300 became the model for all modern single-rotor helicopters, and in 1941, Sikorsky Aircraft got its first contract from the U.S. Army Air Corps for an observation helicopter that became known for life-saving missions in military and civil emergencies.

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Option: B
Explanation :The Wright brothers, Orville and Wilbur were two American aviation pioneers generally credited with inventing, building, and flying the world’s first successful airplane. They made the first controlled sustained flight of a powered heavier-than-air aircraft with the Wright Flyer on December-17-1903, four miles south of Kitty Hawk, North Carolina. In 1904–05, the brothers developed their flying machine into the first practical fixed-wing aircraft the Wright Flyer III. Although not the first to build experimental aircraft, the Wright brothers were the first to invent aircraft controls that made fixed-wing powered flight possible.

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Option: C
Explanation :The telescope is one of humankind’s most important inventions. The simple device that made far away things look near gave observers a new perspective.
The first person to apply for a patent for a telescope was a Dutch eyeglass maker named Hans Lippershey (or Lipperhey). In 1608, Lippershey laid claim to a device that could magnify objects three times. His telescope had a concave eyepiece aligned with a convex objective lens.
In 1609, Galileo Galilei heard about the “Dutch perspective glasses” and within days had designed one of his own — without ever seeing one. He made some improvements — his could magnify objects 20 times — and presented his device to the Venetian Senate. Galileo was the first to point a telescope skyward. He was able to make out mountains and craters on the moon, as well as a ribbon of diffuse light arching across the sky — the Milky Way. He also discovered the rings of Saturn, sunspots and four of Jupiter’s moons.

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Option: C
Explanation :ICMP (Internet Control Message Protocol) is an error-reporting protocol network devices like routers use to generate error messages to the source IP address when network problems prevent delivery of IP packets. ICMP creates and sends messages to the source IP address indicating that a gateway to the Internet that a router, service or host cannot be reached for packet delivery. Any IP network device has the capability to send, receive or process ICMP messages.
ICMP messages are transmitted as datagrams and consist of an IP header that encapsulates the ICMP data. ICMP packets are IP packets with ICMP in the IP data portion. ICMP messages also contain the entire IP header from the original message, so the end system knows which packet failed

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Option: B
Explanation :The DHCP employs a connectionless service model, using the User Datagram Protocol (UDP). It is implemented with two UDP port numbers for its operations.The DHCP employs a connectionless service model, using the User Datagram Protocol (UDP). It is implemented with two UDP port numbers for its operations
UDP (User Datagram Protocol) is an alternative communications protocol to Transmission Control Protocol (TCP) used primarily for establishing low-latency and loss-tolerating connections between applications on the internet.
Both UDP and TCP run on top of the Internet Protocol (IP) and are sometimes referred to as UDP/IP or TCP/IP.Where UDP enables process-to-process communication, TCP supports host-to-host communication. TCP sends individual packets and is considered a reliable transport medium; UDP sends messages, called datagrams, and is considered a best-effort mode of communications.

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Option: C
Explanation :The command line vty 0 4 places you in a prompt that will allow you to set or change your Telnet password.

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Option: A
Explanation :Network Control Protocol is used to help identify the Network layer protocol used in the packet.
Network Control Protocol (NCP) is a set of protocols forming a part of Point − to − Point Protocol (PPP). PPP is a data link layer protocol that is used to transmit multiprotocol data between two directly connected (point-to-point) computers. PPP is composed of link control protocol (LCP), authentication protocol (AP) and network control protocol (NCP). NCPs are used for negotiating the parameters and facilities for the network layer. For every higher-layer protocol supported by PPP, one NCP is there.

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Option: D
Explanation :The command copy flash tftp will prompt you to back up an existing IOS in flash to a TFTP host.

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Option: D
Explanation :802.11 Applies to wireless LANs and provides 1 or 2 Mbps transmission in the 2.4 GHz band using either frequency hopping spread spectrum (FHSS) or direct sequence spread spectrum (DSSS).
802.11a An extension to 802.11 that applies to wireless LANs and provides up to 54-Mbps in the 5GHz band. 802.11a uses an orthogonal frequency division multiplexing encoding scheme rather than FHSS or DSSS.
802.11b Also referred to as 802.11 High Rate or Wi-Fi, is an extension to 802.11 that applies to wireless LANS and provides 11 Mbps transmission (with a fallback to 5.5, 2 and 1-Mbps) in the 2.4 GHz band. 802.11b uses only DSSS.
802.11e A wireless draft standard that defines the Quality of Service (QoS) support for LANs, and is an enhancement to the 802.11a and 802.11b wireless LAN (WLAN) specifications.
802.11g Applies to wireless LANs and is used for transmission over short distances at up to 54-Mbps in the 2.4 GHz bands.

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Option: B
Explanation :The command to back up the configuration on a router is copy running-config startup-config.

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