The system enters ROM monitor mode if the router does not find a valid operating system image, or if a user
interrupts the boot sequence. From ROM monitor mode, a user can boot the device or perform diagnostic
tests.
Answer option A is incorrect. If the router does not have a configuration file, it will automatically enter Setup
mode when the user switches it on. Setup mode creates an initial configuration.
Answer option B is incorrect. Privileged EXEC is used for setting operating parameters.

The Link Layer of TCP/IP model is the networking scope of the local network connection to which a host is attached. This is the lowest component layer of the Internet protocols, as TCP/IP is designed to be hardware independent. As a result, TCP/IP has been implemented on top of virtually any hardware networking technology in existence. The Link Layer is used to move packets between the Internet Layer interfaces of two different hosts on the same link. The processes of transmitting and receiving packets on a given link can be controlled both in the software device driver for the network card, as well as on firmware or specialized chipsets.
Answer option B is incorrect. The Internet Layer of the TCP/IP model solves the problem of sending packets across one or more networks. Internetworking requires sending data from the source network to the destination network. This process is called routing. IP can carry data for a number of different upper layer protocols.
Answer option D is incorrect. The Transport Layer of TCP/IP model is responsible for end-to-end message transfer capabilities independent of the underlying network, along with error control, segmentation, flow control, congestion control, and application addressing (port numbers). End to end message transmission or connecting applications at the transport layer can be categorized as either connection-oriented, implemented in Transmission Control Protocol (TCP), or connectionless, implemented in User Datagram Protocol (UDP).
Answer option is incorrect. The Application Layer of TCP/IP model refers to the higher-level protocols used by most applications for network communication. Examples of application layer protocols include the File Transfer Protocol (FTP) and the Simple Mail Transfer Protocol (SMTP). Data coded according to application layer protocols are then encapsulated into one or more transport layer protocols, which in turn use lower layer protocols to affect actual data transfer.

The Network News Transfer Protocol (NNTP) is an Internet application protocol used for transporting Usenet news articles (netnews) between news servers and for reading and posting articles by end user client applications. NNTP is designed so that news articles are stored in a central database, allowing the subscriber to select only those items that he wants to read. Answer option D is incorrect. Network Time Protocol (NTP) is used to synchronize the timekeeping among the number of distributed time servers and clients. It is used for the time management in a large and diverse network that contains many interfaces. In this protocol, servers define the time, and clients have to be synchronized with the defined time. These clients can choose the most reliable source of time defined from the several NTP servers for their information transmission. Answer option C is incorrect. The Data Link Switching Client Access Protocol (DCAP) is an application layer protocol that is used between workstations and routers for transporting SNA/NetBIOS traffic over TCP sessions. It was introduced in order to address a few deficiencies by the Data Link Switching Protocol (DLSw). The DLSw raises the important issues of scalability and efficiency, and since DLSw is a switch-to-switch protocol, it is not efficient when implemented on workstations. DCAP was introduced in order to address these issues. Answer option B is incorrect. The BOOTP protocol is used by diskless workstations to collect configuration information from a network server. It is also used to acquire a boot image from the server.

Following are the steps required in an idle scan of a closed port:
1.Probe the zombie's IP ID: The attacker sends a SYN/ACK to the zombie. The zombie, unaware
of the SYN/ACK, sends back a RST, thus disclosing its IP ID.

2.Forge a SYN packet from the zombie: In response to the SYN, the target sends a RST. The zombie ignores the unsolicited RST, and the IP ID remains unchanged.

3.Probe the zombie's IP ID again: The zombie's IP ID has increased by only 1 since step 1. So the port is closed.

An automatic fire alarm system is designed for detecting the unwanted presence of fire by monitoring environmental changes associated with combustion. In general, a fire alarm system is classified as either automatically actuated, manually actuated, or both. Automatic fire alarm systems are intended to notify the building occupants to evacuate in the event of a fire or other emergency, to report the event to an off-premises location in order to summon emergency services, and to prepare the structure and associated systems to control the spread of fire and smoke.
Answer option B is incorrect. A fire suppression system is used in conjunction with smoke detectors and fire alarm systems to improve and increase public safety.
Answer option D is incorrect. Gaseous fire suppression is a term to describe the use of inert gases and chemical agents to extinguish a fire.
Answer option A is incorrect. A fire sprinkler is the part of a fire sprinkler system that discharges water when the effects of a fire have been detected, such as when a predetermined temperature has been reached.