Top 32 Bluetooth Technology Interview Questions You Must Prepare 20.Jul.2024

Q1. How Does Bluetooth Fit In With Wifi?

The 802.11b (WiFi) standard is commonly used for wireless networking. Bluetooth is not a competitor with 802.11b, but rather a complement to it. While 802.11b is generally a replacement for wired local area networking, Bluetooth is more commonly used as a replacement for cables between individual devices. Bluetooth is designed to link devices within a very short range (up to 33 feet ). Bluetooth is part of the 802.15 standard.

Q2. What Are Different Classes In Bluetooth?

Bluetooth is a radio standard and communications protocol primarily designed for low power consumption, with a short range (power class dependent: 1 meter, 10 meters, 100 meters) based around low-cost trceiver microchip in each device.

Bluetooth lets these devices communicate with each other when they are in range. The devices use a radio communications system, so they do not have to be in line of sight of each other, and can even be in other rooms, so long as the received power is high enough.

Q3. Will Other Rf (radio Frequency) Devices Interfere With Bluetooth Devices?

No. Bluetooth radios operate on the unlicensed 2.4 GHz (Industrial, Scientific and Medical) frequency band that is shared among other devices (microwave ovens, cordless phones, garage door openers, etc. ). Bluetooth radios switch frequencies at such a rapid pace (1,600 times per second) and the data packets are so small that interference from other RF sources is highly unlikely. Bluetooth is a robust communication system.

Q4. Define Dos Attack?

Denial Of Service attack. It attempts for making computer resources unavailable to its intended users. Its concerted efforts of a person are to prevent a site or service from functioning efficiently, temporarily or indefinitely. The target site categories are banks, credit card payment gateways and root name servers.

Q5. Name Few Applications Of Bluetooth?

  • Wireless control of and communication between a cell phone and a hands free headset or car kit. This is the most popular use.
  • Wireless networking between PCs in a confined space and where little bandwidth is required.
  • Wireless communications with PC input devices such as mouses and keyboards and output devices such as printers.
  • Trfer of files between devices via OBEX.
  • Trfer of contact details, calendar appointments, and reminders between devices via OBEX.
  • Replacement of traditional wired serial communications in test equipment, GPS receivers and medical equipment.
  • For remote controls where infrared was traditionally used.
  • Sending small advertisements from Bluetooth enabled advertising hoardings to other, discoverable, Bluetooth devices.
  • Wireless control of a games console, Nintendo's Wii and Sony's PlayStation 3 will both use Bluetooth technology for their wireless controllers.
  • Sending commands and software to the upcoming LEGO Mindstorms NXT instead of infra red.

Q6. Will Bluetooth And Wireless Lan (wlan) Interfere With Each Other?

No, both Bluetooth and WLAN can co-exist. Since Bluetooth devices use Frequency Hopping and most WLANs use Direct Sequence Spreading techniques they each appear as background noise to the other and should not cause any perceivable performance issues.

Q7. What Is The History Of Bluetooth?

Bluetooth was initiated by Ericsson, IBM, Intel, Nokia and Toshiba in early 199@These companies later formed a special interest group known as the Bluetooth SIG. The Bluetooth 1.0 specifications were released on July 26, 1999, but the technology has only recently become inexpensive enough for widespread use.

Q8. How Many Devices Can Communicate Concurrently?

A Bluetooth device playing the role of the “master” can communicate with up to 7 devices playing the role of the “slave”. This network of “group of up to 8 devices” (1 master + 7 slaves) is called a piconet. A piconet is an ad-hoc computer network of devices using Bluetooth technology protocols to allow one master device to interconnect with up to seven active slave devices (because a three-bit MAC address is used). Up to 255 further slave devices can be inactive, or parked, which the master device can bring into active status at any time.

Q9. Define Bluetooth Dongle?

Bluetooth dongle is a technology that enables a PC for point to multi-point friendly connectivity with other similar Bluetooth devices, like PDA, mobile phone. The devices enable the communication between devices within a range of 30 feet apprx.

Certain recent desktops and laptops are built-in with Bluetooth dongle to communicate. Bluetooth enables a single adapter to allow multiple devices for communicating with one system to another.

Q10. What Is Pairing?

Pairs of devices may establish a trusted relationship by learning (by user input) a shared secret known as a “passkey”. A device that wants to communicate only with a trusted device can cryptographically authenticate the identity of the other device. Trusted devices may also encrypt the data that they exchange over the air so that no one can listen in.

The encryption can however be turned off and passkeys are stored on the device's file system and not the Bluetooth chip itself. Since the Bluetooth address is permanent a pairing will be preserved even if the Bluetooth name is changed. Pairs can be deleted at any time by either device. Devices will generally require pairing or will prompt the owner before it allows a remote device to use any or most of its services. Some devices such as Sony Ericsson phones will usually accept OBEX business cards and notes without any pairing or prompts. Certain printers and access points will allow any device to use its services by default much like unsecured Wi-Fi networks.

Q11. Can You Please Explain The Difference Between Bluetooth And Infra Red?

  • Connectivity: One-to-one connections are made by infrared devices, while Bluetooth devices can form when all the devices have identified themselves to each other. 
  • Versatility: Bluetooth devices could work together; where as infrared devices need to be specially designed for specific devices.
  • Range: Class 3 Bluetooth devices works at about 30 feet; while infrared is rated at 3 feet.
  • Orientation: Infrared devices are direct line-of-sight; where as Bluetooth devices could communicate even in times of separation by obstacles. Security: Bluetooth is less secure than infrared due to the omni directional nature; where as infrared signals could only be intercepted by a device.

Q12. What Is Bluetooth Sig?

Bluetooth Special Interest Group (SIG) :  Bluetooth wireless technology is revolutionizing personal connectivity by providing freedom from wired connections. It is a specification for a small-form factor, low-cost radio solution providing links between mobile computers, mobile phones, other portable handheld devices and automobiles, as well as connectivity to the Internet.

The Bluetooth SIG, comprised of leaders in the telecommunications, computing, automotive and consumer electronics industries, is driving development of the technology and bringing it to market.

The Bluetooth SIG includes Promoter member companies Agere, Ericsson, IBM, Intel, Microsoft, Motorola, Nokia and Toshiba, and thousands of Associate and Adopter member companies. The Bluetooth SIG, Inc. headquarters are located in Overland Park, Kas, U.S.A.

Q13. What Are Some Of The Uses Of Bluetooth?

Depending on the Bluetooth profiles included on the device, Bluetooth technology has the capability to wirelessly synchronize and trfer data among devices. The Bluetooth audio capabilities can be used for headset and hands free applications. The exact functionality provided by a Bluetooth enabled device depends on the Bluetooth profiles included.

Q14. What Is It - A Technology, A Standard, An Initiative, Or A Product?

Bluetooth wireless technology is a de facto standard, as well as a specification for small-form factor, low-cost, short range radio links between mobile PCs, mobile phones and other portable devices. The Bluetooth Special Interest Group is an industry group consisting of leaders in the telecommunications, computing, and networking industries that are driving development of the technology and bringing it to market

Q15. Define Cabir Worm?

Cabir worm is one of the malicious software, usually referred as malware. It utilizes Bluetooth technology for sending itself to another similarly vulnerable device. As it is self-replicative, is it classified as a worm.

Cabir worms are currently affects mobile phone which uses the Symbian Series 60 User Interface Platform and feature Bluetooth wireless technology.

Q16. What Is The Range Of Bluetooth Trmitter/receivers?

Bluetooth is designed for very low power use, and the trmission range will only be 10m, about 30ft. High-powered Bluetooth devices will enable ranges up to 100m (300ft). Considering the design philosophy behind Bluetooth, even the 10m range is adequate for the purposes Bluetooth is intended for. Later versions of the Bluetooth spec may allow longer ranges.

Q17. Define Bluetooth Profiles?

Order to describe the way of implementing user models accomplishments, the profiles are developed. A number of user scenarios are described by the user models where Bluetooth performs the radio trmission. Profile stack describes the options in each protocol which are mandatory for each profile, and defines range of parameters for each protocol. The profiles are concerned for decreasing the risk of interoperability issues among various products of different manufacturers.

Q18. What Types Of Companies Are Likely To Adopt Or Promote Bluetooth Technology?

Companies likely to adopt this technology include, but are not limited to, software developers, network vendors, silicon vendors, peripheral and camera manufacturers, mobile PC and handheld device manufacturers, consumer electronics manufacturers and more.

Q19. What Companies Are Involved In The Bluetooth Initiative?

Global technology leaders Ericsson, Nokia, IBM, Intel and Toshiba founded the Bluetooth SIG in 199@These companies are now supported by over 1,000 other organizations with a wide range of expertise, including Widcomm, Inc.

Q20. Is Bluetooth Practical For Use With Mobile Devices?

Yes. One concern for mobile computing users is power consumption. Bluetooth radios are very low power, drawing as little as 0.3mA in standby mode and 30mA during sustained data trmissions. Bluetooth radios alternate among power-saving modes in which device activity is lowered to maximize the mobile power supply.

Q21. What Kind Of Encryption Will Be Used For Bluetooth Security?

The Bluetooth specification 1.0 describes the link encryption algorithm as a stream cipher using 4 LFSR (linear feedback shift registers). The sum of the width of the LFSRs is 128, and the spec says “the effective key length is selectable between 8 and 128 bits”.

This arrangement allows Bluetooth to be used in countries with regulations limiting encryption strength, and “facilitate a future upgrade path for the security without the need for a costly redesign of the algorithms and encryption hardware” according to the Bluetooth specification. Key generation and authentication seems to be using the 8-round SAFER+ encryption algorithm.

The information available suggests that Bluetooth security will be adequate for most purposes; but users with higher security requirements will need to employ stronger algorithms to ensure the security of their data.

Q22. What Are Bluetooth Profiles?

A profile is a description of how to use a specification to implement a particular function. The International Standards Organization (ISO) first came up with the idea of profiles. In Bluetooth, there are several profiles available and they are arranged in a hierarchical fashion. For example, in order to use the headset profile, a device must also include the lower level profiles such as the serial port and general access profiles.

Q23. Are Different Brands Of Bluetooth Products Compatible?

Yes. They have to. The Bluetooth Logo Certification Program requires Bluetooth products to interoperate with products manufactured by other vendors; those products that don't interoperate will not be allowed to use the Bluetooth logo.

Q24. How Secure A Bluetooth Device Is?

Bluetooth uses the SAFER+ algorithm for authentication and key generation. The E0 stream cipher is used for encrypting packets. This makes eavesdropping on Bluetooth-enabled devices more difficult.

Q25. What Is The Data Throughput Speed Of A Bluetooth Connection?

Bluetooth trfers data at a rate of 721 Kbps, which is from three to eight times the average speed of parallel and serial ports, respectively. This bandwidth is capable of trmitting voice, data, video and still images

Q26. What Is Lmp (link Management Protocol)?

Multiple data links are combined for the formation of a single traffic engineering link, for the purpose of scale ability. The in-band messaging is not restricted by the management of TE links, but can be utilized by using out-of-band techniques.

The Link Management Protocol runs between a pair of nodes and is utilized for managing TE links. LMP is specifically used for maintaining control channel connectivity, verifying the physical connectivity of the data links, correlating the link property information, suppressing downstream alarms and localizing the link failures for protection/restoration purposes.

Q27. What Are The Problems With Older Versions (1.0 And 1.0 B)?

Versions 1.0 and 1.0 B had numerous problems and the various manufacturers had great difficulties in making their products interoperable. 1.0 and 1.0B also had mandatory Bluetooth Hardware Device Address (BD_ADDR) trmission in the handshaking process, rendering anonymity impossible at a protocol level, which was a major setback for services planned to be used in Bluetooth environments, such as Consumerism.

Q28. Define Ip Spoofing?

Sending messages by intruder to a computer system with an IP address that indicates the message is sent from a trusted host, for gaining unauthorized access to computer systems. The hacker/intruder first utilize a variety of techniques for finding an IP address of a trusted host. Later he modifies the packet headers, in order to give an illusion that the packets are sent from the host.

Q29. Describe Ldap And Also Define Its Uses?

Lightweight Directory Access Protocol is one of the directory service protocols. It runs over TCP/IP. LDAP directory services implements a client/server model. Directory data is available on one or more LDAP servers. The server responds with a pointer to another LDAP server.

Uses: LDAP allows the users to access the information in the directory to change. Online telephone directories and email directories are some of the uses of LDAP. LDAP directory has utilities to modify, delete, and search the entries.

Q30. Can You Please Explain The Difference Between Power Classes In Bluetooth?

Device Power Class, Max Output Power (mW), Max Output Power (dBm), Expected Range

  • Class 1, 100mW, 20dBm, 100m.
  • Class 2, 2.5mW, 4dBm, 10m.
  • Class 3, 1mW, 0dBm, 10cm.

Q31. Is Bluetooth An Ieee Standard, Like Ieee 802.11 And Ethernet?

Being an IEEE standard will be a big plus to widespread adoption of Bluetooth, and IEEE 802.15 working group for personal area networks (PAN) announced that they will be adopting Bluetooth as the IEEE 802.15 standard.

Q32. Why Is Bluetooth 2.0 Better?

The main features of Bluetooth Core Specification Version 2.0 + EDR are:

  • 3 times faster trmission speed (up to 10 times in certain cases)
  • Lower power consumption through reduced duty cycle
  • Simplification of multi-link scenarios due to more available bandwidth
  • Backwards compatible to earlier versions
  • Further improved BER (Bit Error Rate) performance