Question 1

Compared with asynchronous protocols, synchronous data link protocols typically provide what performance characteristic during transmission on serial links?

Accepted Answer

Introduction: Serial communications can be organized as asynchronous or synchronous. The distinction affects framing overhead, timing recovery, and achievable throughput. This question asks which performance characteristic is typically associated with synchronous protocols. Given Data / Assumptions: Synchronous links share a common clock or embed timing so characters/frames do not need per-character start/stop bits. Asynchronous links add start/stop bits to each character and do not depend on a shared clock. We compare typical throughput under similar line conditions. Concept / Approach: Synchronous protocols (e.g., HDLC/SDLC) frame blocks of data with minimal per-character overhead. Clocking is continuous or recovered, so the line can be used efficiently with fewer overhead bits per payload bit. Asynchronous protocols add start and stop bits to every character (often 10 bits per 8-bit character), reducing efficiency and limiting maximum useful throughput on the same physical line. Hence, for a given signaling rate, synchronous protocols usually achieve higher effective data rates. Step-by-Step Solution: Identify overhead differences: async adds start/stop per character; sync does not.Relate overhead to efficiency: fewer overhead bits → higher throughput.Map to the offered choices: “allow faster transmission than asynchronous protocols do.”Select that as the correct statement. Verification / Alternative check: Line efficiency calculations show typical async 8N1 uses 10 bits per byte (80% efficiency before other overhead), whereas sync frames can approach near 100% efficiency for large blocks. Why Other Options Are Wrong: Transmit characters one at a time (A): describes asynchronous character framing, not synchronous block/frame transfer. Generally used by personal computers (C): both types are used; not a defining truth. Are more reliable (D): reliability depends on error control, not strictly sync vs. async. None of the above (E): invalid because option B is correct. Common Pitfalls: Equating “synchronous” with “parallel” or assuming reliability is intrinsic rather than a function of framing and error control. Final Answer: allow faster transmission than asynchronous protocols do

Question 2

In teleprinter-era character encoding, how many bits per symbol does the Baudot code (ITA2) use for representing characters?

Accepted Answer

Introduction: Historical codes help explain the evolution from telegraphy and teletype systems to modern 8-bit and Unicode encodings. Baudot code (more precisely ITA2) was widely used for teleprinters and early data communications. Given Data / Assumptions: The question refers to the classic Baudot/ITA2 code used in teletype systems. We are counting the number of bits per transmitted character symbol. No parity or start/stop framing bits are included in the requested count—only the symbol itself. Concept / Approach: Baudot (ITA2) represents characters using 5 bits per symbol. Because 5 bits alone cannot encode the full alphabet, digits, and punctuation, Baudot employs shift characters to toggle between “letters” and “figures” modes, effectively multiplexing two symbol tables. This economical bit width matched the bandwidth constraints of early telecommunication channels. Step-by-Step Solution: Recall that ITA2 defines 5-bit codes plus special shift/ltr/figs codes.Differentiate symbol bits from line framing (start/stop) added by asynchronous links.Confirm the canonical figure: 5 bits per Baudot/ITA2 symbol.Select the option “5.” Verification / Alternative check: Teleprinter documentation (e.g., Teletype Model 33/35) lists 5-bit code points and the letters/figures shifts used to extend the character set. Why Other Options Are Wrong: 1 bit: insufficient to encode a useful set of symbols. 8 or 9 bits: correspond to later encodings (ASCII uses 7 bits; extended ASCII/bytes are 8 bits). None of the above: invalid because 5 is correct. Common Pitfalls: Confusing line framing (start/stop/parity) with symbol width; Baudot codewords are 5 bits, even if the serial frame carries additional bits. Final Answer: 5

Question 3

If odd parity is used for ASCII error detection on an 8-bit character (7 data bits plus one parity bit), what can be said about the number of 0s in each transmitted 8-bit symbol?

Accepted Answer

Introduction: Parity is a simple error-detection method that constrains the count of 1s or 0s in a transmitted symbol. When using odd parity, the total number of 1s in the codeword (data bits plus parity bit) is forced to be odd. This question probes whether that constraint uniquely determines the number of 0s. Given Data / Assumptions: We transmit 8-bit symbols (7-bit ASCII data + 1 parity bit). Odd parity means total count of 1s in the 8-bit symbol is odd. No additional constraints are imposed on the data bits. Concept / Approach: If the number of 1s is constrained to be odd, the number of 0s equals 8 minus the number of 1s. Because “odd” could be 1, 3, 5, or 7 ones, the number of 0s could be 7, 5, 3, or 1 respectively. Therefore the number of 0s is not fixed—it varies with the data. The only thing determined by odd parity is the parity of the 1s count, not the exact zero count. Step-by-Step Solution: Let ones = any odd value in {1, 3, 5, 7} (theoretically 9 is impossible in 8 bits).Compute zeros = 8 − ones; possible zeros ∈ {7, 5, 3, 1}.Observe that zeros are neither always odd nor always even.Conclude the correct description is “indeterminate.” Verification / Alternative check: Test examples: send 0000000 (seven zeros) with parity 1 → 1 one and 7 zeros; send 1110000 with parity 0 → 4 ones (not allowed with odd parity), adjust to 1110001 → 5 ones and 3 zeros. The zeros count changes across valid codewords. Why Other Options Are Wrong: Even or odd (A, B): each can occur depending on the data; neither is guaranteed. 42 (D): humorous distractor; unrelated to parity counts. None of the above (E): invalid because “indeterminate” correctly captures the variability. Common Pitfalls: Assuming that constraining ones also constrains zeros to a fixed parity. In fixed-length words, zeros parity flips as data changes. Final Answer: indeterminate

Question 4

In classic telecom offerings, which of the following is an example of a medium-speed, switched communications service appropriate for data connections?

Accepted Answer

Introduction: Before modern broadband and packet-switched services became ubiquitous, businesses often leased or dialed into switched services that provided modest data rates sufficient for terminals, transaction systems, and early computer communications. Identifying representative offerings helps contextualize legacy network design. Given Data / Assumptions: We are concerned with medium-speed and switched services—not dedicated high-speed private lines. The terms reflect historical product names from common carriers. The question seeks a specific example recognized in exam-oriented literature. Concept / Approach: Dataphone 50 is a known Bell/AT&T family designation for switched data services offering mid-range speeds (e.g., tens of kilobits per second in some variants) suitable for interactive terminals and host access. While DDD (Direct Distance Dialing) is a public switched voice service rather than a specialized data service, and “Series 1000” is not a widely cited switched data product in standard networking curricula, “Dataphone 50” aligns with the intended category. Step-by-Step Solution: Clarify the scope: switched, carrier-provided, medium-speed data capability.Evaluate options: Dataphone 50 is specifically a carrier data service brand.Exclude DDD as voice-oriented and Series 1000 as not standard in this context.Select Dataphone 50 as the best-fit example. Verification / Alternative check: Telecom references list Dataphone-branded services as dial-up or switched offerings distinct from leased private lines, often used with modems or DSUs for enterprise connectivity. Why Other Options Are Wrong: Series 1000 (A): not a canonical switched data service in typical exam catalogs. DDD (C): refers to switched voice dialing, not a data-specific service. All of the above (D): incorrect because the set includes non-data or unclear entries. None of the above (E): invalid because Dataphone 50 fits. Common Pitfalls: Assuming any switched telephone offering is a data service; data-grade services had specific branding, conditioning, and performance guarantees. Final Answer: Dataphone 50

Question 5

Regarding the legacy HOSTS file used for static name-to-address mappings, what is the maximum number of entries that can be configured?

Accepted Answer

Introduction: Operating systems maintain a local text file (commonly called HOSTS) to map hostnames to IP addresses before or in addition to querying DNS. Understanding limitations of this file is helpful for troubleshooting name resolution or designing lab environments without DNS. Given Data / Assumptions: We refer to typical UNIX-like and Windows implementations where HOSTS is a plain text file parsed at lookup time. Entries follow a straightforward format: IP address followed by one or more hostnames/aliases. No formal numeric cap is defined in the specification. Concept / Approach: The HOSTS file is line-oriented text, and operating systems read and parse it sequentially. There is no standardized, fixed upper bound on the number of entries. Practical limits arise from system memory, parser performance, and administrative manageability rather than a hard-coded entry count. As a result, the best answer in exam contexts is that the HOSTS file supports an effectively unlimited number of entries (subject to practical constraints). Step-by-Step Solution: Identify HOSTS as a text database read by the resolver.Note absence of a standards-defined entry ceiling.Acknowledge performance/maintenance constraints rather than a strict limit.Select “Unlimited.” Verification / Alternative check: Vendor documentation focuses on format and precedence (e.g., hosts file vs. DNS) without specifying maximum row counts, reinforcing the notion of no hard limit. Why Other Options Are Wrong: 8, 255, 500: arbitrary values; not general OS-imposed maxima. None of the above: invalid because “Unlimited” is the accepted characterization. Common Pitfalls: Confusing practical manageability (huge files slow lookups) with imposed numeric caps; “unlimited” here means no fixed, standardized limit. Final Answer: Unlimited

Question 6

In local area networking, which transmission medium is traditionally associated with broadband LANs that use frequency-division techniques and multiple channels?

Accepted Answer

Introduction: LANs historically used two contrasting physical-layer styles: baseband, sending one digital signal over the medium at a time, and broadband, partitioning spectrum into multiple channels using frequency-division techniques. Knowing which media align with each style clarifies legacy Ethernet variants and campus cabling choices. Given Data / Assumptions: “Broadband local networks” refers to LANs using multiple RF-like channels over the same medium. We compare common LAN media: coaxial cable, optical fiber, UTP (twisted pair), and CATV (a system rather than a bare medium). We seek the traditional association in networking curricula. Concept / Approach: Broadband LANs (e.g., early IEEE 802.7 and 10Broad36) used coaxial cable because its shielding and frequency response support multiple modulated channels on one physical plant—much like community antenna television (CATV) systems. By contrast, classic Ethernet over UTP (10BASE-T/100BASE-TX) is baseband; fiber in LANs is also typically used for baseband digital signaling (though fiber can carry many wavelengths, “broadband LAN” historically maps to coaxial implementations). Step-by-Step Solution: Identify broadband = FDM, multiple simultaneous channels.Match to coaxial cable’s widespread use in broadband/CATV and 10Broad36.Recognize UTP and typical LAN fiber as baseband in standard Ethernet deployments.Select “Coaxial cable.” Verification / Alternative check: Standards histories show 10Broad36 (broadband Ethernet over 75-ohm coax) alongside baseband 10BASE5/10BASE2, confirming coax’s role. Why Other Options Are Wrong: optic fiber: commonly baseband in LAN Ethernets; broadband in telecom WDM context, but not the historic “broadband LAN” answer. CATV: a system that often uses coax; the question asks for a medium. UTP: baseband Ethernet medium. None of the above: invalid because coaxial cable is correct. Common Pitfalls: Confusing broadband vs. baseband, or mixing the CATV system concept with the underlying medium choice. Final Answer: Coaxial cable

Question 7

History of the Internet: The birthplace of the World Wide Web (WWW) is widely regarded as which organization and research laboratory?

Accepted Answer

Introduction: The World Wide Web (WWW) transformed the Internet from a technical research network into a global information space accessible to ordinary users. Knowing where the Web originated helps students distinguish the Web from the Internet and recognize the role of research institutions in foundational technologies. Given Data / Assumptions: The question asks about the birthplace of the World Wide Web, not the Internet itself. Answer choices include government agencies, a private company, and a European research organization. We focus on the site where the Web’s core concepts and first implementations were created and demonstrated. Concept / Approach: The Web consists of three key building blocks: URLs for addressing resources, HTTP for transfer, and HTML for hypertext documents. These were proposed and implemented by Tim Berners-Lee (with colleagues) at a physics research center. The earliest Web server and browser prototypes were also built there, along with the first public website and the initial hypertext content model. Step-by-Step Solution: 1) Separate “Web” from “Internet”: the Internet predates the Web by decades.2) Identify the lab where URLs, HTTP, and HTML were first specified and implemented.3) Recognize that this occurred at CERN (European Organization for Nuclear Research) in Geneva.4) Conclude that CERN is the birthplace of the World Wide Web. Verification / Alternative check: Historical timelines consistently cite CERN’s internal proposal (1989) and first operational web services (1990–1991). The world’s first website was hosted at info.cern.ch, further cementing CERN’s role. Why Other Options Are Wrong: the Department of Defense: funded ARPANET foundations but not the Web itself. ARPA: pivotal for packet switching and TCP/IP, not the Web’s invention. Netscape: commercialized browsers later; did not invent the Web. None of the above: incorrect because CERN is correct. Common Pitfalls: Confusing the Internet’s origin (ARPANET, U.S. initiatives) with the Web’s origin (CERN, Europe). Another mistake is crediting a later browser company with inventing the entire Web. Always distinguish protocol layer history from application-layer innovation. Final Answer: CERN

Question 8

Token Ring vs. Ethernet efficiency: Token Ring uses a circulating token so that only one station transmits at a time, eliminating collisions. As the Token-Ring network grows in node count and physical extent, what is the overall effect on throughput…

Accepted Answer

Introduction / Context: Token Ring networks eliminate collisions by passing a token that grants transmit permission. This makes channel access deterministic compared to contention methods such as CSMA/CD in legacy shared Ethernet. However, determinism does not mean scalability without limits. As more stations join or as the ring length grows, token rotation time and latency increase, influencing effective throughput and user experience. Given Data / Assumptions: A single token circulates to serialize access. More nodes imply longer token rotation time. Physical ring length and repeaters introduce propagation and processing delay. Frame sizes and station holding times are bounded by the ring rules. Concept / Approach: In Token Ring, the average wait to transmit is proportional to token rotation time. As nodes increase, each station must wait longer for the token to return. While collisions are avoided, airtime is consumed by token passing overhead, frame headers, and propagation delays. Queueing delays grow with offered load and station count, so aggregate efficiency (useful payload/total time) declines at scale. Step-by-Step Solution: Recognize that only one station can transmit at a time because of the token.As node count or ring length increases, token rotation time increases.Longer rotation and more queueing reduce effective throughput per node.Therefore, overall efficiency drops as the network grows. Verification / Alternative check: Performance models of token passing networks show that average access delay grows with the number of stations and their traffic intensity. Empirical measurements on large rings confirm increasing latency and decreasing goodput per station at high node counts. Why Other Options Are Wrong: An additional token per 1,000 nodes: classic Token Ring uses a single token; multiple tokens complicate stability.Mandatory 16 Mbps above 500 nodes: speed choice is a design parameter, not a strict threshold rule.Replace MAU with “Hyperstation” device: not a standard requirement or technology.More efficient: contradicts increased delays and overhead. Common Pitfalls: Assuming “no collisions” equals “infinite scalability.” Deterministic access still incurs overhead and growing wait times with scale. Final Answer: The network becomes less efficient.

Question 9

OSI fundamentals: at the application layer (Layer 7), which statement best describes the layer’s role in providing the user’s logical entry point into the networked communication system?

Accepted Answer

Introduction / Context: The OSI model separates networking into seven conceptual layers. The topmost, the application layer, interacts most closely with user-facing processes and provides services that applications leverage to communicate. Understanding the precise responsibilities of this layer prevents confusion with transport/session functions. Given Data / Assumptions: Layer 7 interfaces with software applications and offers network services to them. Terms like “virtual circuits” are typically associated with transport/session behavior, not Layer 7. We must choose the statement that best captures the Layer 7 role. Concept / Approach: The application layer acts as the user’s logical “port” into the network—exposing services such as file transfer, email, and directory access. While the software executing on an endpoint uses all layers, the distinctive function at Layer 7 is to provide an interface and services to the application, not to create/maintain transport-level circuits. Step-by-Step Solution: Identify the Layer 7 mandate: service interface for applications.Differentiate from Layer 4/5 duties (connections, sessions, virtual circuits).Select the statement that emphasizes “user’s port into the network.” Verification / Alternative check: Classic descriptions of OSI Application layer (Layer 7) highlight service provision to user processes and direct user interaction through protocols like HTTP, FTP, and SMTP, confirming the “user’s port” phrasing. Why Other Options Are Wrong: Establishes/maintains/terminates virtual circuits: aligned with transport/session, not Layer 7.“Consists of software being run”: too vague; software exists at many layers and does not specify Layer 7’s role.All of the above: incorrect because option A is not a Layer 7 responsibility.None of the above: incorrect because option B is accurate. Common Pitfalls: Attributing transport/session responsibilities to the application layer; thinking any endpoint software equals Layer 7. Final Answer: defines the user's port into the network.

Question 10

Legacy access hardware: what is the name of the modem device that connects to the telephone system by pressing the telephone handset into two rubber cups on the unit?

Accepted Answer

Introduction / Context: Before direct-connect modems became common, early data communication often used a device that converted digital signals to audible tones and sent them through a phone handset physically pressed into the unit. Knowing this historical device helps understand the evolution of modem technology and telecommunication interfaces. Given Data / Assumptions: The phone’s handset is inserted into flexible receptacles (“rubber cups”). The device converts digital data to audio frequencies and vice versa. Used with plain old telephone service handsets in the pre-RJ11 era or in restricted environments. Concept / Approach: Such a device is an acoustic coupler. It transmits and receives tones through the handset’s microphone and earpiece, avoiding a direct electrical connection to the phone network. Gateways, bridges, and multiplexers perform network routing/segmenting/aggregation roles and do not match this description. Step-by-Step Solution: Match the physical “handset into cups” description to historical modem types.Recognize this is exactly how acoustic couplers operate.Select “acoustic coupler.” Verification / Alternative check: Museum references and early computing texts depict acoustic couplers (e.g., 300 bps) where the handset is clamped into rubber mounts to exchange audio tones. Why Other Options Are Wrong: Gateway/bridge: network-layer/link-layer devices for traffic forwarding.Time-division multiplexer: aggregates multiple channels; not a handset-coupled modem.None of the above: incorrect as “acoustic coupler” fits perfectly. Common Pitfalls: Confusing any modem with this specific handset-coupled design; modern modems use direct line interfaces, not acoustic coupling. Final Answer: acoustic coupler.

Question 11

Local Area Network (LAN) properties: which of the following is a key characteristic of LAN design and operation?

Accepted Answer

Introduction / Context: LANs interconnect devices over a limited geographic area and are engineered for high bandwidth, low latency, and straightforward management. A critical design goal is to keep the network independent of any single application, so many applications can run over the same infrastructure without modification. Given Data / Assumptions: LANs should support diverse application traffic (file sharing, voice, video, print). Physical and link layers are standardized (e.g., Ethernet, Wi-Fi). The question asks for a general characteristic, not a niche optimization. Concept / Approach: “Application independent interfaces” means the LAN exposes standardized services and frames that do not depend on any particular application. This decoupling maximizes interoperability and longevity. By contrast, “unlimited expansion” is false—LANs face practical limits (broadcast domains, switch capacity). “Low cost access for low bandwidth channels” describes WAN dial-up more than LANs. “Parallel transmission” is a specific physical-layer technique, not a defining LAN characteristic. Step-by-Step Solution: Identify the statement aligning with layered design and interoperability.Eliminate claims that contradict known limits or describe WAN traits.Choose “application independent interfaces.” Verification / Alternative check: Ethernet’s success stems from a generic frame service used by countless applications and protocols, demonstrating application independence. Why Other Options Are Wrong: Unlimited expansion: LANs are constrained by broadcast and switching limits.Low cost access for low bandwidth channels: WAN/dial-up attribute, not LAN.Parallel transmission: an implementation detail, not a universal LAN property.None of the above: incorrect because option A is correct. Common Pitfalls: Assuming LANs scale indefinitely without segmentation; conflating physical-layer techniques with architectural characteristics. Final Answer: application independent interfaces.

Question 12

Protocol definition: a protocol is a set of rules governing the time sequence of events that must take place at which relationship level?

Accepted Answer

Introduction / Context: In layered network architectures, adjacent layers interact via service interfaces, whereas like-numbered layers on different hosts communicate using protocols. Understanding this separation clarifies the difference between service primitives and protocol data units, and avoids mislabeling device-to-device behaviors as protocol-layer interactions. Given Data / Assumptions: Protocols specify formats, timings, and semantics between entities at the same layer. Interfaces describe how one layer offers services to the layer above. The question asks where protocol rules apply. Concept / Approach: Protocols govern communication between peers—for example, TCP on one host with TCP on another. Across an interface, the relationship is service provision/consumption, not protocol peer exchange. “Between modems” names a device pair, not a layer relationship. “Between an interface” is grammatically incorrect and conceptually imprecise. Step-by-Step Solution: Recall: peers exchange PDUs following protocol rules.Interfaces expose services but do not define peer protocol behavior.Select “between peers.” Verification / Alternative check: OSI terminology distinguishes Service Access Points (interfaces) from protocols (peer-to-peer rules). This confirms the selection. Why Other Options Are Wrong: Between modems: hardware scope, not a layer-agnostic definition.Across an interface: describes service, not protocol.“Between an interface”: malformed and incorrect.None of the above: incorrect because “between peers” is right. Common Pitfalls: Confusing service interfaces with protocols; conflating device roles with layer relationships. Final Answer: between peers.

Question 13

Optical communications basics: approximately how much optical power can a typical LED (light-emitting diode) source couple into a multimode optical fiber?

Accepted Answer

Introduction / Context: Optical transmitters for short-range data links may use LEDs or laser diodes. LEDs are inexpensive and robust but have lower coupling efficiency and optical power than lasers. Knowing the order of magnitude for LED launch power into multimode fiber helps with link budget estimation and selection of components for campus or in-building networks. Given Data / Assumptions: We refer to typical, order-of-magnitude coupled power into multimode fiber. No optical amplifiers are used. We compare realistic LED values versus laser-class outputs. Concept / Approach: Typical LED coupled power into multimode fiber is on the order of tens to a few hundred microwatts (roughly −15 dBm to −10 dBm). Values in the milliwatt range are characteristic of laser diodes, not LEDs. Picowatt levels are far below normal transmitter output and would not sustain practical links. Therefore, 100 microwatts is a sensible “ballpark” figure for LED launch power into fiber. Step-by-Step Solution: Eliminate unrealistically low power (picowatts) as non-viable for links.Eliminate milliwatt-level power as laser territory, not typical LEDs.Choose a microwatt-level value consistent with common LED transmitters. Verification / Alternative check: Vendor datasheets for legacy 850 nm LED transmitters show coupled powers in the −20 dBm to −10 dBm range (10 to 100 microwatts), aligning with the 100 microwatts estimate. Why Other Options Are Wrong: 440 microwatts: unusually high for standard LED coupling; more in line with efficient sources or short-range lasers.100 picowatts: orders of magnitude too low.10 milliwatts: typical of laser diodes, not LEDs.None of the above: incorrect because 100 microwatts is appropriate. Common Pitfalls: Assuming all optical sources have similar power; ignoring that coupling loss and numerical aperture further reduce the launched power. Final Answer: 100 microwatts.

Question 14

Practical online capabilities: with telecommunications and a personal computer, which of the following activities are feasible through typical online services and networks?

Accepted Answer

Introduction / Context: The combination of a personal computer and telecommunications (dial-up, broadband, cellular) opens access to many online services. Historically and today, users can download software, purchase products, and even request postal delivery services through online intermediaries. Recognizing the breadth of these capabilities is essential for basic computer literacy exams. Given Data / Assumptions: Users connect to public networks and service providers. “Public domain programs” and freeware are commonly distributed online. Hybrid services can convert electronic messages into printed mail for postal delivery. E-commerce platforms frequently provide discounts relative to retail pricing. Concept / Approach: Each listed activity corresponds to well-established online services: software distribution sites and repositories for downloads; hybrid mail services for printing and posting letters; and online marketplaces for discounted goods. Therefore, the comprehensive answer that includes all items is correct. Step-by-Step Solution: Map each option to a real-world online service category.Verify that none of the items conflict with typical network capabilities.Select the comprehensive option “All of the above.” Verification / Alternative check: Historical bulletin board systems and modern app stores support downloads; hybrid mail has existed via numerous providers; e-commerce discounts are ubiquitous. Why Other Options Are Wrong: Each single-activity option is incomplete.“None of the above” contradicts well-known online capabilities. Common Pitfalls: Confusing freeware with illegal copying; assuming postal delivery requires in-person visits—hybrid services bridge digital and physical mail. Final Answer: All of the above.

Question 15

Binary conversion practice: convert the decimal number 224 to its 8-bit binary representation.

Accepted Answer

Introduction / Context: Converting between decimal and binary is a foundational skill in computer science and networking. IP addressing, subnet masks, and many low-level operations rely on bitwise reasoning. Here we convert the decimal value 224 into an 8-bit binary string suitable for byte-oriented contexts (e.g., subnet masks such as 255.255.255.224). Given Data / Assumptions: We need an 8-bit representation (values 0–255). Decimal input is 224. Standard positional weights are 128, 64, 32, 16, 8, 4, 2, 1. Concept / Approach: Binary expansion expresses a number as a sum of powers of 2. Determine which place values are needed by subtracting the largest possible powers of 2 without making the running total negative. Place a 1 where a weight is used and a 0 where it is not. Step-by-Step Solution: Start with the highest weight: 128 fits into 224 → remainder 224 - 128 = 96 → bit pattern starts 1xxxxxxx.Next 64 fits into 96 → remainder 96 - 64 = 32 → pattern 11xxxxxx.Next 32 fits into 32 → remainder 32 - 32 = 0 → pattern 111xxxxx.Remaining weights (16, 8, 4, 2, 1) all exceed the remainder of 0 → bits are 0.Final 8-bit pattern: 11100000. Verification / Alternative check: Reconstruct from bits: 1128 + 164 + 132 + 016 + 08 + 04 + 02 + 01 = 224, confirming correctness. Why Other Options Are Wrong: 11110000 = 240, not 224.00011110 = 30, not 224.00001111 = 15, not 224.None of the above: incorrect because 11100000 is correct. Common Pitfalls: Reversing bit order (LSB/MSB confusion) or stopping after setting the first few bits without confirming the remainder is zero. Final Answer: 11100000.

Question 16

Windows troubleshooting: which command-line utility is specifically used to view and troubleshoot NetBIOS over TCP/IP name resolution (e.g., remote name table, cache)?

Accepted Answer

Introduction / Context: NetBIOS name resolution (for legacy Windows networking) differs from DNS. When browsing or connecting to shares fails due to name issues, a tool that exposes the NetBIOS name cache, remote name tables, and sessions is needed to diagnose the problem accurately. Given Data / Assumptions: Operating environment is Windows or compatible systems supporting NetBIOS over TCP/IP. Goal is to inspect name tables, cache, and sessions for NetBIOS. We are not simply measuring connectivity or listing TCP ports. Concept / Approach: NBTSTAT is the dedicated utility for NetBIOS over TCP/IP. It can display local and remote NetBIOS name tables, purge and reload the cache, and show NetBIOS sessions. In contrast, Netstat shows active sockets and routing; Ping tests IP reachability; Hostname prints the local machine’s name only and does not troubleshoot NetBIOS names. Step-by-Step Solution: Identify the troubleshooting scope: NetBIOS names, not generic TCP/UDP ports.Map each tool to its function and eliminate those unrelated to NetBIOS names.Select NBTSTAT as the correct utility. Verification / Alternative check: Commands like “nbtstat -n”, “nbtstat -c”, and “nbtstat -A ” directly query or flush NetBIOS name information, confirming its focus. Why Other Options Are Wrong: Netstat: lists connections and listening ports; not NetBIOS name tables.PING: tests ICMP reachability; does not diagnose NetBIOS naming.Hostname: shows local name only; no remote or cache insight.None of the above: incorrect because NBTSTAT is correct. Common Pitfalls: Assuming DNS and NetBIOS use the same tools; they have different caches and diagnostics. Final Answer: NBTSTAT.

Question 17

TCP/IP verification sequence: after confirming that TCP/IP is installed correctly on a host, what is the next best step to verify the configuration locally before testing external connectivity?

Accepted Answer

Introduction / Context: Troubleshooting TCP/IP should proceed from the inside out. Verifying the local stack first isolates configuration or driver issues on the host before involving switches, routers, DNS, or Internet reachability. A systematic progression avoids chasing external problems when the fault is local. Given Data / Assumptions: TCP/IP is installed but end-to-end connectivity is untested. We want the next immediate validation step. Local verification should not depend on any external network devices. Concept / Approach: The first active test is to ping the local host address (commonly 127.0.0.1 or the host’s own assigned IP). This confirms the IP stack, ICMP handling, and internal loopback interface. Only after local verification should you proceed to test the default gateway, same-subnet hosts, remote routers, and finally Internet destinations. Step-by-Step Solution: Use “ping 127.0.0.1” to validate the IP stack and loopback.If successful, ping the local NIC’s assigned IP to validate binding and interface status.Then ping the default gateway and progress outward to remote hosts. Verification / Alternative check: If loopback ping fails, the problem is local (stack or firewall). Success on loopback but failure to the gateway suggests link/VLAN issues rather than stack problems. Why Other Options Are Wrong: Broadcast address: may be filtered and is not a safe initial test.Microsoft website: depends on DNS, routing, and Internet; too many variables.Distant router: requires LAN, routing, and ACLs to work; not the next local step.None of the above: incorrect because local ping is correct. Common Pitfalls: Jumping straight to Internet pings and misdiagnosing local adapter or driver problems as ISP issues; forgetting host firewalls may block ICMP. Final Answer: Ping the address of the local host.

Question 18

In IP-based enterprise and campus networking, which standard protocol is primarily used for network management and monitoring tasks such as reading/writing Management Information Base (MIB) variables and receiving asynchronous alerts (traps) from de…

Accepted Answer

Introduction / Context: Network administrators need a consistent way to monitor device health, collect performance counters, change configuration parameters safely, and receive alerts when something goes wrong. Over IP networks, this role is served by a well-known management protocol implemented in routers, switches, firewalls, servers, printers, and many IoT devices. Given Data / Assumptions: The question is about a standard protocol for network management features over IP. Common management tasks include querying counters, setting parameters, and receiving traps or notifications. Devices expose data via a structured hierarchy (Management Information Base, or MIB). Concept / Approach: Simple Network Management Protocol (SNMP) is the de facto standard for IP network management. Managers (NMS tools) issue Get, GetNext, GetBulk, and Set operations to agents running on devices, which expose MIB objects. Devices can also send unsolicited Trap or Inform messages to notify about events (e.g., link down, temperature threshold, authentication failure). SNMP exists in versions v1, v2c, and v3; SNMPv3 adds user-based security with authentication and privacy (encryption). Step-by-Step Solution: Identify the protocol that queries and modifies MIB objects on agents: SNMP. Confirm support for asynchronous notifications: Traps/Informs are part of SNMP. Validate that it is the widely adopted standard across multi-vendor devices. Therefore, select SNMP as the correct answer. Verification / Alternative check: Operationally, NMS platforms (e.g., open-source and commercial tools) use SNMP polling to build time-series graphs (CPU, memory, interface throughput) and rely on SNMP traps for events. Vendor MIBs extend the standard MIB-II to expose model-specific information, illustrating the breadth and standardization of SNMP-based management. Why Other Options Are Wrong: SNA: IBM Systems Network Architecture; not the IP-era standard for general network management. FTP: a file transfer protocol; not a management protocol. SMS: short message service; unrelated to network device management. Telnet: interactive terminal access; useful for manual administration but not for structured monitoring. Common Pitfalls: Confusing command-line access (Telnet/SSH) with programmatic management; assuming syslog alone is enough (syslog complements SNMP events but does not provide structured polling). Also, using SNMPv2c community strings without restricting access can expose sensitive device data—prefer SNMPv3 for security. Final Answer: SNMP

Question 19

On a typical Local Area Network (LAN), different computers are connected by a cable and a Network Interface Card (NIC). Which component completes each host’s physical/logical connection to the LAN medium?

Accepted Answer

Introduction / Context: Every device on a Local Area Network (LAN) must physically and logically attach to the network medium (twisted-pair copper, fiber, or radio). The hardware component that performs framing, media access, and physical signaling for a host is the Network Interface Card (NIC), also called a network adapter. Understanding this role distinguishes NICs from WAN devices like modems or from generic cabling. Given Data / Assumptions: The LAN uses cabling (e.g., Ethernet over twisted pair or fiber) or equivalent access medium. Each computer requires a hardware interface that implements Layer 1/Layer 2 functions. The question asks for the device that completes the LAN connection on the host side. Concept / Approach: The NIC presents a MAC address, implements Ethernet (or Wi-Fi) framing, and handles the physical encoding/decoding of signals. It connects to the LAN via a port (e.g., RJ-45 for copper or SFP for fiber) and interacts with OS drivers to send and receive frames. Without a NIC, a computer cannot participate on the LAN even if a cable is present. Step-by-Step Solution: Identify the host-side hardware that provides MAC/PHY functions: the NIC. Differentiate from WAN adapters like modems that translate digital signals to analog carriers. Confirm that cabling alone is not sufficient; an interface is required to generate/interpret frames. Choose “Interface card” (NIC) as the correct option. Verification / Alternative check: Device managers in operating systems list Ethernet/Wi-Fi adapters with drivers; removing or disabling a NIC prevents LAN participation. Network throughput counters and link status LEDs on NIC ports further demonstrate that the NIC is the essential interface between the host and the LAN medium. Why Other Options Are Wrong: Modem: used for wide-area analog/digital adaptation, not LAN Ethernet connectivity. Special wires: cabling is necessary but not sufficient; needs an interface. Telephone lines: not the standard LAN medium; applicable to PSTN/DSL, not Ethernet LANs. Wireless access point: infrastructure device for Wi-Fi; the host still needs a wireless NIC to connect. Common Pitfalls: Confusing a switch port with the host adapter; assuming a USB-to-Ethernet dongle is not a NIC (it is—just external). Also, mixing up modem and NIC terminology in small-office contexts. Final Answer: Interface card

Question 20

The classic EIA-232 (RS-232-C) serial interface originally specified a 25-pin connector. How many pins are present on this standard connector?

Accepted Answer

Introduction / Context: EIA-232 (often known by its historical name RS-232-C) defines electrical characteristics and signal assignments for serial communications between Data Terminal Equipment (DTE) and Data Communication Equipment (DCE). While many PCs later adopted a smaller 9-pin connector, the original standard interface used a larger 25-pin connector with defined signal pins for control and data. Given Data / Assumptions: We are referring to the classic EIA-232/RS-232-C connector as originally standardized. The question asks for the number of pins on that standard connector. Later variants (DE-9) exist but do not change the original pin count. Concept / Approach: The original RS-232-C physical interface specified a DB-25 connector with 25 pins. These pins include transmit data, receive data, signal ground, and numerous control leads (e.g., RTS, CTS, DTR, DSR, DCD, RI). Many applications used only a subset, which is why the industry later favored the compact DE-9 connector that multiplexed key signals into 9 pins, but the standardized full connector remains 25-pin. Step-by-Step Solution: Identify the historical standard: RS-232-C → DB-25 physical connector. Recall the full signal set includes many control lines beyond TX/RX. Therefore, the connector has 25 pins. Select the option “25.” Verification / Alternative check: Pinout references list DB-25 pin assignments for RS-232-C. Serial adapters and legacy modems commonly expose DB-25 ports, confirming the 25-pin count even if modern PCs commonly present DE-9 ports for convenience. Why Other Options Are Wrong: 20/24/30: not the standardized DB-25 count for RS-232-C. 9: applies to the later DE-9 connector, not the original RS-232-C connector in the question. Common Pitfalls: Assuming all RS-232 connectors are 9-pin because of later PC hardware; overlooking that the standard historically describes a 25-pin interface. Final Answer: 25

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