50+ CRED Interview Questions and Answers

Requirements and capacity of stm-1 link implementation

• Requirements include fiber optic cables, SDH equipment, and proper configuration

• Capacity of stm-1 link is 155.52 Mbps

• STM-1 link is commonly used in telecommunications for high-speed data transmission

Subnet mask is used to divide an IP network into subnetworks, determining the network and host portions of an IP address.

• Subnet mask is a 32-bit number that separates the network and host portions of an IP address.

• To calculate the number of usable IPs in a subnet, subtract 2 from the total number of IPs in the subnet.

• Network host IP is the first IP address in a subnet, while broadcast IP is the last IP address in a subnet.

• For example, in a subnet with a subnet mask of 255.255...read more

OSI model is a conceptual model that characterizes and standardizes the communication functions of a telecommunication or computing system.

• OSI model has 7 layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

• Each layer has a specific function and communicates with the layers above and below it.

• Linked list is a data structure that consists of nodes linked together in a sequence.

• Each node contains data and a pointer to the next node in the lis...read more

To upgrade software in OLT, ONT, and Tejas 1400 locally and from NMS, follow these steps.

• Locally: Use a USB drive to transfer the software update file to the device. Access the device's management interface and initiate the upgrade process.

• From NMS: Use the Network Management System (NMS) to remotely push the software update to the devices. Schedule the upgrade during off-peak hours to minimize disruption.

• Ensure compatibility: Check the release notes of the software update to...read more

MPLS stands for Multiprotocol Label Switching. It is a protocol used in high-performance telecommunications networks.

• Advantages of MPLS include improved performance, scalability, quality of service, and traffic engineering capabilities

• MPLS allows for efficient packet forwarding based on labels instead of IP addresses

• MPLS can support different types of traffic, such as voice, video, and data, with different service levels

• MPLS is often preferred for large networks with high tra...read more

Virtual memory is still necessary even with large physical memory. Paging helps manage memory usage.

• Virtual memory allows for efficient use of physical memory by swapping data between RAM and storage devices.

• Paging helps manage memory usage by dividing memory into smaller chunks called pages, which can be swapped in and out of physical memory as needed.

• Even with large physical memory, virtual memory can still be useful for running multiple applications simultaneously or for h...read more

Different kinds of cards used in Tejas 1400 and 1600 mux include line cards, switch cards, and power cards.

• Line cards: used for connecting the mux to external devices

• Switch cards: used for routing data within the mux

• Power cards: used for providing power to the mux

• Examples: STM-1 line card, STM-4 switch card, power supply card

Layer-2 and layer-3 services refer to different levels of network services in the OSI model.

• Layer-2 services operate at the data link layer and include functions like MAC address assignment and Ethernet switching.

• Layer-3 services operate at the network layer and include functions like IP address assignment and routing.

• The main difference between layer-2 and layer-3 services is the level at which they operate in the OSI model.

• Layer-2 services are more focused on local network ...read more

An IP address is a unique numerical label assigned to each device connected to a computer network. IPv4 uses 32-bit addresses, while IPv6 uses 128-bit addresses.

• IP address is a unique identifier for devices on a network.

• IPv4 uses 32-bit addresses, represented in decimal format (e.g. 192.168.1.1).

• IPv6 uses 128-bit addresses, represented in hexadecimal format (e.g. 2001:0db8:85a3:0000:0000:8a2e:0370:7334).

Code for producer-consumer problem using mutex

• Create a shared buffer between producer and consumer

• Use mutex to lock the buffer while accessing it

• Producer adds data to buffer and signals consumer

• Consumer waits for signal and consumes data from buffer

• Repeat until all data is produced and consumed

GPON technology is a type of passive optical network that uses fiber-optic cables to deliver high-speed internet, TV, and phone services.

• GPON stands for Gigabit Passive Optical Network

• It uses a point-to-multipoint architecture, where a single optical fiber serves multiple users

• GPON architecture includes an Optical Line Terminal (OLT) at the service provider's central office and Optical Network Terminals (ONTs) at the customer premises

• Data is transmitted using time-division mu...read more

When an OSPF broadcast domain is broken into 2 and then back to 1, the DR and BDR election process will be triggered again.

• When the broadcast domain is split, each segment will have its own DR and BDR elected based on priority and router ID.

• When the broadcast domain is merged back into one, a new DR and BDR election will take place among all routers in the domain.

• The election process considers the priority value set on each router, with higher priority routers having a better...read more

Different types of alarms in Tejas equipments include power alarms, temperature alarms, and communication alarms.

• Power alarms: indicate issues with power supply or voltage levels

• Temperature alarms: alert when equipment temperature exceeds safe limits

• Communication alarms: signal problems with data transmission or network connectivity

Segmentation is the process of dividing a larger entity into smaller parts or segments.

• It is commonly used in image processing to separate objects from the background.

• Segmentation can also refer to dividing a market into smaller groups based on demographics or behavior.

• In computer science, segmentation refers to dividing memory into smaller parts for more efficient use.

• Segmentation can also be used in biology to divide cells or tissues into smaller parts for analysis.

Program to find the duplicate in an array using binary tree or hash table

• Create a binary tree or hash table

• Iterate through the array and insert each element into the tree or table

• If an element already exists, it is a duplicate

IPv4 address of Google DNS server is 8.8.8.8 and IPv6 address is 2001:4860:4860::8888.

• IPv4 address: 8.8.8.8

• IPv6 address: 2001:4860:4860::8888

The main difference between xa60g and xa20g cards is the processing power and memory capacity.

• xa60g card has higher processing power and memory capacity compared to xa20g card

• xa60g card is more suitable for high-performance computing tasks

• xa20g card may be more cost-effective for less demanding applications

Virtual addressing is a memory management technique that allows a program to use more memory than physically available.

• Virtual addresses are mapped to physical addresses by the operating system.

• Virtual addresses are allocated to a program during its execution.

• Virtual addressing allows for efficient use of memory resources.

• Virtual addressing enables the use of shared memory and memory protection.

• Examples of virtual addressing include paging and segmentation.

Different types of networking devices include routers, switches, hubs, modems, access points, and firewalls.

• Routers: Used to connect multiple networks together and route data between them.

• Switches: Used to connect devices within a network and manage traffic efficiently.

• Hubs: Used to connect multiple devices in a network, but they operate at a lower level than switches.

• Modems: Used to modulate and demodulate digital data for transmission over analog communication lines.

• Access ...read more

Nodes can be added and deleted in NMS by using the management interface or command line interface.

• Nodes can be added through the management interface by selecting the 'Add Node' option and providing the necessary information such as IP address, hostname, and SNMP credentials.

• Nodes can also be added through the command line interface by using specific commands to add a new node to the network management system.

• To delete a node, navigate to the 'Delete Node' option in the manag...read more

OSI model is a conceptual model that characterizes and standardizes the communication functions of a telecommunication or computing system.

• OSPF (Open Shortest Path First) is a routing protocol used for Internet Protocol (IP) networks.

• DNS (Domain Name System) is a hierarchical and decentralized naming system for computers, services, or other resources connected to the Internet.

• DHCP (Dynamic Host Configuration Protocol) is a network management protocol used to dynamically assig...read more

To find the middle of a linked list, use two pointers - one moving at twice the speed of the other.

• Initialize two pointers - slow and fast

• Move the slow pointer one step at a time and the fast pointer two steps at a time

• When the fast pointer reaches the end of the list, the slow pointer will be at the middle

• If the list has even number of nodes, there will be two middle nodes. In that case, return the second middle node

An IP address is a unique numerical label assigned to each device connected to a computer network, while a subnet mask is used to divide an IP network into subnetworks.

• IP address identifies a device on a network, like 192.168.1.1

• Subnet mask determines the network portion of an IP address, like 255.255.255.0

• Subnet mask is used to separate the network and host portions of an IP address

Mutex and Semaphores serve different purposes in managing concurrent access to shared resources.

• Mutex is used to provide exclusive access to a shared resource, while Semaphores can be used to control access to a shared resource by multiple threads.

• Mutex is binary in nature, meaning it can only be in two states - locked or unlocked, while Semaphores can have multiple states.

• Mutex is typically used for protecting critical sections of code, while Semaphores can be used for synch...read more

Linker links object files and libraries to create an executable file. Loader loads the executable file into memory and executes it.

• Linker resolves external references and generates an executable file

• Loader loads the executable file into memory and performs relocation

• Linker and loader are part of the toolchain used to build and run programs

• Example: gcc uses linker and loader to compile and run C programs

Time complexity of building a heap using linked list and arrays

• Building a heap using a linked list takes O(nlogn) time complexity

• Building a heap using an array takes O(n) time complexity

• Linked list implementation is slower than array implementation

• Arrays are better for random access while linked lists are better for insertion and deletion

Program to merge two sorted linked lists in sorted order

• Create a new linked list to store the merged result

• Compare the first nodes of both lists and add the smaller one to the result list

• Move the pointer of the list with the smaller node to the next node

• Repeat until one of the lists is empty, then add the remaining nodes of the other list to the result

• Return the merged list

OSI and TCP/IP models are networking models that define how data is transmitted over a network.

• OSI model has 7 layers: Physical, Data Link, Network, Transport, Session, Presentation, Application.

• TCP/IP model has 4 layers: Network Interface, Internet, Transport, Application.

• OSI model is theoretical while TCP/IP model is practical and widely used.

• OSI model is a reference model while TCP/IP model is a protocol stack.

• Example: OSI model helps in understanding how data flows in a n...read more

DCCR stands for Data Center Control Room and DCCM stands for Data Center Construction Manager.

• DCCR is a centralized location within a data center where operators monitor the performance of servers, networks, and other equipment.

• DCCM is responsible for overseeing the construction and maintenance of data center facilities.

• Examples: DCCR helps in ensuring smooth operations of data centers by monitoring and managing resources efficiently. DCCM ensures that data center constructio...read more

SDH structure refers to the hierarchy of synchronous digital signals, while SDH frame is the basic unit of data transmission in SDH networks.

• SDH structure includes various levels such as STM-1, STM-4, STM-16, etc.

• SDH frame consists of a fixed number of bytes, with overhead for management and error correction.

• SDH frame structure includes sections, lines, and paths for data transmission.

• Example: STM-1 is a common level in SDH structure, with a data rate of 155.52 Mbps.

VLAN stands for Virtual Local Area Network. VLAN ID is a unique identifier assigned to a VLAN.

• VLAN is a logical grouping of devices on the same network segment.

• VLANs help in segmenting network traffic for security and performance reasons.

• VLAN ID is a number assigned to each VLAN to differentiate it from others.

• For example, VLAN 10 might be used for finance department while VLAN 20 for marketing.

Deadlock can be prevented by using techniques like resource allocation, avoidance, and detection.

• Use a resource allocation algorithm to ensure resources are allocated in a safe manner.

• Avoidance can be achieved by ensuring that resources are only requested when they are available.

• Detection involves periodically checking for deadlock and taking action to resolve it if it is detected.

• Implementing timeouts can also help prevent deadlock by releasing resources that are not being u...read more

L2VPN, VPLS, and VPWS are technologies used in networking to provide virtualized Layer 2 connectivity.

• L2VPN (Layer 2 Virtual Private Network) is a technology that allows for the extension of a Layer 2 network over a Layer 3 network.

• VPLS (Virtual Private LAN Service) is a type of L2VPN that connects multiple sites in a single bridged domain.

• VPWS (Virtual Private Wire Service) is a point-to-point L2VPN service that provides a dedicated connection between two sites.

• These technol...read more

Mutex is used for mutual exclusion while Semaphore is used for signaling and synchronization.

• Mutex is used to protect a shared resource from simultaneous access by multiple threads.

• Semaphore is used to signal between threads or to limit the number of threads accessing a shared resource.

• Mutex can only be locked and unlocked by the thread that locked it.

• Semaphore can be signaled and waited on by different threads.

• Mutex is binary, meaning it has only two states: locked and unloc...read more

OSPF (Open Shortest Path First) is a routing protocol used to determine the best path for data packets in a network.

• OSPF is used to efficiently route traffic in large networks by calculating the shortest path between routers.

• It is a link-state routing protocol that uses Dijkstra's algorithm to determine the best path.

• OSPF is preferred over other routing protocols like RIP due to its faster convergence time and scalability.

• It supports VLSM (Variable Length Subnet Masking) and ...read more

STM-1 link refers to a Synchronous Transport Module level 1 link used in telecommunications for transmitting data.

• STM-1 link operates at a data rate of 155.52 Mbps.

• It is commonly used in SDH (Synchronous Digital Hierarchy) networks.

• STM-1 link can carry multiple DS3 or E3 circuits.

• It is equivalent to 63 E1 channels or 28 DS1 channels.

The question is about finding a duplicate in a string.

• Convert the string into an array of characters

• Create a HashSet to store unique characters

• Iterate through the array and check if each character is already present in the HashSet

• If a character is already present, it is a duplicate

AC works by converting electrical energy into mechanical energy to create a cooling effect. Efficiency can be improved by using energy-efficient components and regular maintenance.

• AC works by using a compressor to convert electrical energy into mechanical energy, which is used to pump refrigerant through the system to create a cooling effect.

• Efficiency can be improved by using energy-efficient components such as high SEER rated units, proper insulation, and regular maintenanc...read more

Expected CTC and take home should be based on industry standards and the candidate's experience and skills.

• Expected CTC should be in line with industry standards for the position and the candidate's experience level.

• Take home pay should be calculated after deductions like taxes and insurance.

• Candidates can research average salaries for similar roles in the industry to get an idea of what to expect.

• Negotiation is common during salary discussions, so be prepared to justify your...read more

Comparator vs Comparable, Streams, Lambda Expression

• Comparator and Comparable are interfaces used for sorting objects in Java

• Comparator is used for custom sorting logic, while Comparable is used for natural sorting order

• Streams are a sequence of elements that can be processed in parallel or sequentially

• Lambda expressions are used to write concise and functional code in Java

5G is the next generation of wireless technology, offering faster speeds, lower latency, and increased capacity compared to 4G.

• 5G offers faster speeds than 4G, with potential download speeds of up to 10 Gbps compared to 4G's 100 Mbps.

• 5G has lower latency, meaning faster response times for applications like gaming and video streaming.

• 5G has increased capacity to support more devices and data traffic compared to 4G.

• 5G technology uses higher frequency bands than 4G, which allows...read more

Deadlock is a situation where two or more processes are unable to proceed because they are waiting for each other to release resources.

• Occurs in multi-threaded or multi-process environments

• Can lead to system freeze or crash

• Prevention techniques include resource ordering and timeouts

• Example: Process A holds resource X and waits for resource Y, while Process B holds resource Y and waits for resource X

VCG stands for Voltage Controlled Gain and VCAT stands for Voltage Controlled Attenuator.

• VCG is a circuit that adjusts the gain of an amplifier based on a control voltage.

• VCAT is a circuit that adjusts the attenuation of a signal based on a control voltage.

• Both VCG and VCAT are commonly used in electronic devices to control signal levels.

• Example: VCG can be used in audio amplifiers to adjust the volume based on user input.

• Example: VCAT can be used in RF communication systems ...read more

A network management system is designed to monitor and control network devices and ensure their efficient operation.

• The system should have a centralized dashboard to display real-time network status and performance metrics.

• It should support automated network discovery and device configuration management.

• The system should provide alerts and notifications for network events and failures.

• It should have the ability to generate reports and analyze network data for troubleshooting ...read more

Test_and_Set program is used to ensure mutual exclusion in concurrent systems.

• Test_and_Set is a hardware instruction that sets a memory location to a value and returns its old value.

• The program uses a loop to repeatedly execute the Test_and_Set instruction until it returns 0.

• The program then enters the critical section and sets the memory location back to 0 when done.

• Example code: while(Test_and_Set(&lock)); //critical section lock = 0;

Job back and if field refers to the tasks and responsibilities of a network field engineer.

• Job back involves troubleshooting network issues in the field

• Field work includes installing and configuring network equipment

• Network field engineers may also perform maintenance and upgrades on existing networks

Main parameters of active electronics components include voltage, current, power, frequency, and temperature.

• Voltage: The operating voltage range of the component.

• Current: The maximum current that can flow through the component.

• Power: The power dissipation capability of the component.

• Frequency: The frequency response of the component.

• Temperature: The operating temperature range of the component.

Conductor, capacitor, and resistor are basic components used in electronic circuits.

• Conductor: Allows the flow of electric current. Example: Copper wire.

• Capacitor: Stores and releases electrical energy. Example: Ceramic capacitor.

• Resistor: Limits the flow of electric current. Example: Carbon film resistor.

ES6, also known as ECMAScript 2015, is the sixth major release of the JavaScript language that introduced new features and syntax improvements.

• Introduced let and const for variable declarations

• Added arrow functions for more concise syntax

• Included classes for object-oriented programming

• Introduced template literals for easier string interpolation

• Added default parameters and rest parameters for functions

5G in telecom refers to the fifth generation of wireless technology, promising faster speeds, lower latency, and increased capacity for mobile networks.

• 5G is the next generation of mobile network technology after 4G LTE.

• It promises faster download and upload speeds, lower latency, and increased capacity for more connected devices.

• 5G uses higher frequency bands to achieve these improvements, but with shorter range compared to 4G.

• It enables technologies like Internet of Things ...read more

Salary is the payment or compensation an employee receives from an employer in exchange for work performed.

• Salary is typically paid on a regular basis, such as monthly or bi-weekly.

• It can be a fixed amount or vary based on factors like performance or seniority.

• Salaries can include additional benefits such as health insurance, retirement contributions, and bonuses.

LTE stands for Long-Term Evolution and is a standard for wireless broadband communication.

• LTE is a 4G wireless communication standard used for high-speed data transmission.

• It provides faster data speeds and lower latency compared to previous generations like 3G.

• LTE is commonly used for mobile internet access, video streaming, and VoIP services.

• Examples of LTE networks include Verizon, AT&T, and T-Mobile in the United States.

Golden rules of accounting include consistency, relevance, reliability, comparability, and understandability.

• Consistency: using the same accounting methods and principles consistently over time

• Relevance: ensuring that financial information is relevant to the decision-making needs of users

• Reliability: ensuring that financial information is accurate and can be relied upon

• Comparability: ensuring that financial information can be compared across different periods and companies

• Und...read more

The OSI model is a conceptual framework that standardizes the functions of a telecommunication or computing system into seven layers.

• The OSI model stands for Open Systems Interconnection model.

• It divides network communication into seven layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

• Each layer has specific functions and interacts with adjacent layers for data transmission.

• Example: The Physical layer deals with the physical connection b...read more

Host to host communication refers to the process of data exchange between two devices on a network.

• Host to host communication involves the transmission of data packets between two devices connected to a network.

• It can be achieved through various protocols such as TCP/IP, UDP, HTTP, etc.

• Each device on the network is identified by an IP address, which is used to route the data packets to the correct destination.

• Examples of host to host communication include sending emails, brow...read more

Fiber optics is a technology that uses thin strands of glass or plastic to transmit data as light signals.

• Fiber optics is used for high-speed internet, cable TV, and telephone communication.

• The technology is based on the principle of total internal reflection, which allows light to travel through the fiber without escaping.

• Fiber optic cables are immune to electromagnetic interference and can transmit data over long distances without loss of signal strength.

• Fiber optics is als...read more

Hoisting is a JavaScript mechanism where variable and function declarations are moved to the top of their containing scope during compilation.

• Variable and function declarations are hoisted to the top of their scope.

• Only declarations are hoisted, not initializations.

• Function declarations take precedence over variable declarations.