What are the advantages and disadvantages of WiFi ?

Wi-Fi is an abbreviation of the phrase Wireless Fidelity.


  • Convenient
    • Useful for smartphones, tablet devices and other portable devices to connect at any convenient location within premises.
  • Simplicity
    • To connect a new device with a network, simply turn on the Wi-Fi and do the simple configuration settings.
  • Mobility
    • Internet can be accessed from anywhere, ie. Bus, train, coffee-shop, super market, etc.
  • Expandability
    • It is convenient to add more wireless devices with current hardware settings without any cost and time.
  • Efficiency
    • WiFi enabled devices are used at offices for convenient to access their files at any location and it gives more productivity for the company.
  • Cost Control
    • In WiFi network devices can be added without any cost unlike cables needs to be get man power to do the job.
  • Standardization of Technology
    • Wi-Fi technology has standardized for all countries, it helps for the mobile devices to connect the WiFi regardless of the location.


  • Performance/Speed
    • Although Gigabit WiFi is available in the market, we cannot get the gigabit speed at all locations. Now cable network has 10 Gbps speed.
  • Connectivity/Reliability
    • WiFi signal is depends on the interference. Ie. Concrete wall will reduce the signal strength. Also, there is a limit for distance to connect WiFi signals.
  • Security
    • WiFi router has various encryption methods to secure our network password. Need to be done proper configuration before use the WiFi network.

Samsung Galaxy S8 & S8+

Samsung launched its next Galaxy smart phone series S8 and S8+, end of March 2017 with stunning infinity display, smart assistant Bixby, camera, security, smart switch and many more….

Infinity display:

The revolutionary design of the Galaxy S8 and S8+ begins from the inside out.  The Infinity Display has an incredible end-to-end screen that spills over the phone’s sides, forming a completely smooth, continuous surface with no bumps or angles. It’s pure, pristine, uninterrupted glass. This makes up the entire front of the phone, as it flows seamlessly into its aluminium shell. The result is a beautifully curved, perfectly symmetrical device.


Bixby completely changes the way you interact with your phone. It’s a personal assistant that understands talk, text, and taps so you’re never confined to one mode of communication. It also completely changes the way you use your phone. You don’t even have to ask Bixby, just show it what you want by opening your camera app. It’s so incredibly easy.


Capture life as it happens with the Galaxy S8 and S8+ cameras. The intuitive 12MP rear camera and the 8MP front camera ensure you don’t miss a moment, whether it’s day or night.

Smart switch:

From your photos and videos to contact and music, Smart Switch lets you easily transfer memories from your old phone to your new Galaxy S8 or S8+



Features S8 S8+
Colour Midnighg Black, Orchid Gray and Mapple Gold
Dimensions 148.9 x 68.1 x 8.0 mm 159.5 x 73.4 x 8.1 mm,
Weight 152 g 173 g
Screen Size  5.8 inch 6.2 inch
Resolution 2960 x 1440 , 570ppi 2960 x 1440 , 529 ppi
Camera Front 8MP, Rear 12 MP
Processor Octa-core (2.3GHz Quad + 1.7GHz Quad), 64 bit, 10nm processor
Storage 64 GB * May differ by country and carrier
External Memory Support MicroSD (Up to 256GB)
Memory 4 GB
Network LTE Cat 9 (up to 450Mbps)
SIM Card Dual SIM model (4G + 3G Hybrid slot): one Nano SIM and one Nano SIM or one MicroSD slot (up to 256GB)
Operating System Android 7.0 (Nougat)
Audio Ultra High Quality Audio Playback. Ultra High Quality Audio Playback Supports UHQ 24-bit audio
Video UHD 4K (3840 x 2160) | 30fps
Battery 3000mAh 3500mAh
Charging Ultra Fast Charging, Fast Wireless Charging (Built-in).

*Fast Wireless Charging Pad to be purchased separately.

Authentication Lock Type: Pattern, Pin, Password.

Biometrics Lock Type: Iris Scanner, Fingerprint Scanner, Face Recognition



Making Facebook Live More Accessible With Closed Captions

Facebook announced that the making Facebook accessible to everyone is a key part of building global community. Facebook is allowing publishers to include closed captions in Facebook Live, helping people who are deaf or hard of hearing to experience live videos. Now, if your captioning settings are turned on, you’ll automatically see closed captions on Live broadcasts when they’re available.

Over the past year, daily watch time for Facebook Live broadcasts has grown by more than 4x, and 1 in 5 Facebook videos is a Live broadcast. By enabling publishers to include closed captions with their Live broadcasts, hope more people can now participate in the exciting moments that unfold on Live.

How it works

Closed captions help make video content accessible to everyone in the Facebook community. Facebook now enables publishers to add closed captions to their Facebook Live broadcasts using
the CEA-608 closed captions standard. Captions using this standard can now be ingested into Facebook Live broadcasts through the Facebook Live API.

To enable closed captions:
1. Before you go live, set up a third-party tool or start working with a third-party caption provider to enable live captions for your broadcast. Options include Ai-Media and Telestream.
2. Along with the video footage you capture in your live broadcast, insert or pass through embedded CEA-608 captions data into the live encoder.
3. Stream your live broadcast feed via the Facebook Live API.

People can then view embedded closed captions for your broadcast in a Facebook experience on Android, iOS, or web browsers.


Apple WWDC 2017

Apple’s WWDC 2017 (Worldwide Developers Conference) held on June 5, 2017 at San Jose Convention Center, San Jose, California, USA. There are exciting announcements for iPhone, iPad, imac,iOS, macOS and HomePad.

iPad Pro

  • Redesigned Retina display
  • 5-inch or 12.9-inch model
  • Camera 12 MP / 7MP (Face time HD camera)
  • Up to 10 hours battery life
  • Up to 512 GB Storage
  • 2224 x 1668 resolution
  • A10X Fusion Chip
  • Compatible with Apple Pencil and Smart Keyboard
  • 120 Hz Refresh Rate
  • The world’s most advanced display
  • iOS11
  • More powerful than most PC laptops
  • 866 Mbps WiFi / support 25 LTE bands / up to 450 Mbps via LTE
  • Touch ID 2x faster than previous generation
  • Smart keyboard for both the 10.5-inch and 12.9-inch iPad Pro models.
  • 5-inch 6.1 mm thin and 1 pound
  • 9-inch 6.9 mm thin and 1.5 pounds


iOS 11

iOS 11 makes iPhone better than before. It makes iPad more capable than ever. And now it opens both to amazing possibilities for augmented reality in games and apps. With iOS 11, iPhone and iPad are the most powerful, personal, and intelligent devices they’ve ever been.

  • Wherever they are, they’re here
    • The new Files app brings all your files together. You can easily browse, search, and organize all your files in one place.
  • The new Dock.
    • Bottom line, a more powerful way to work.
    • Better in multiple ways.
  • Drag and Drop.
    • Give it a touch.
  • Apple Pencil.
    • More ways to make your mark.
  • Augmented reality.
    • Apps that can change your world.
  • Apple Pay.
    • Pay friends with a message.
  • Live Photos.
    • Livelier than ever.
    • See your photos in a whole new light.
  • The all-new App Store.
    • Get to apps with fewer taps.
    • Naturally, more helpful.
  • AirPlay 2. Home, sweet-sounding home.
  • Control Center.
    • Make it your own.
  • Lock screen.
    • All your notifications in one handy place
  • Do Not Disturb.
    • When you’re driving, just drive.
    • Stay on course. Indoors and out.
  • Quick Type keyboard.
    • Type with one hand tied behind your back.
  • Automatic Setup.
    • Get off to a quick start.


  • 27-inch iMac with Retina 5K display – 8GB dedicated VRAM ; 4.5 GHz speed
  • 5-inch iMac with Retina 4K display – 4GB dedicated VRAM ; 4.2 GHz speed
  • Seventh generation intel core i5 or i7 processors
  • 43% brighter than previous models
  • Two Thunderbolt 3 (USB-C) ports each delivering up to 40Gb/s data transfer
  • The new Magic Keyboard with Numeric Keypad

iMac Pro (Available December 2017)

  • Processor:
    • 8-, 10-, or 18-core Xeon processor
    • Turbo Boost up to 4.5GHz
    • Up to 42MB cache
  • Radeon Pro Vega:
    • 11 teraflops single precision
    • 22 teraflops half precision
    • 8GB or 16GB High Bandwidth Memory
    • 400 GB/s memory bandwidth
  • Memory:
    • Up to 128GB
    • 2666MHz DDR4 ECC
  • Storage:
    • Up to 4TB SSD
    • 3GB/s throughput
  • I/O:
    • Four Thunderbolt 3 (USB‑C) ports
    • Up to 44 million pixels
    • 10Gb Ethernet
    • Also supports Nbase-T industry-standard 1Gb, 2.5Gb, and 5Gb link speeds.
  • Retina 5K display:
    • 500 nits
    • 43% brighter
    • One billion colors
    • Support for 10-bit spatial and temporal dithering.
  • All-new speakers


macOS High Sierra

macOS High Sierra introduces new core technologies that improve the most essential functions of your Mac. From rearchitecting how it stores your data to improving how you watch videos to unleashing the full power of the graphics processors, it’s all central to today’s Mac experience.

  • Apple File System.
    • Your data is under new management.
  • HEVC. The new standard for video.
    • High Efficiency Video Coding, also known as H.265
  • Virtual reality for Mac.
  • Photos. More ways to edit. More ways to organize. More ways to wow.



A smarter coach and workout partner. Better in tune with your taste in music. And an even more proactive all-day assistant. With watchOS 4, Apple Watch is dialed in to you like never.

  • Activity
    • Daily Inspiration
    • Evening push
    • Monthly Challenge
    • Celebrations
  • Workout
    • Quick start
    • High Intensity Interval Training
    • Enhanced Swim Tracking
    • Gym Equipment Sync
    • Quick switch
    • Do not disturb
  • Music
    • More songs on your wrist
    • Automatic sync
  • All-Day Assistant
    • Siri watch face
    • Kaleidoscope watch face
    • Toy story watch face
    • Person to person payment
    • Apple pay cash
    • News app


HomePod (available December 2017)

HomePod is a powerful speaker that sounds amazing, adapts to wherever it’s playing, and together with Apple Music, gives you effortless access to one of the world’s largest music catalogs. All controlled through natural voice interaction with Siri.1 It takes the listening experience to a whole new level. And that’s just the beginning.

  • Size
    • Dimensions:
    • 8 inches high (172 mm)
    • 6 inches wide (142 mm)
  • Weight:
    • 5 pounds (2.5 kg)
    • Available in two colours
  • Audio Technology
    • High-excursion woofer with custom amplifier
    • Array of seven horn-loaded tweeters, each with its own custom amplifier
    • Six-microphone array for far-field Siri and room sensing
    • Internal low-frequency calibration microphone for automatic bass correction
    • Direct and ambient audio beamforming
    • Transparent studio-level dynamic processing
  • Wireless
    • 11a/b/g/n/ac Wi‑Fi with MIMO
    • Multiroom speaker support with AirPlay 23
  • Languages
    • English (Australia, UK, U.S.)

Google I/O 2017

Google I/O is an annual developer conference held by Google in San Francisco, California on 17 – 19 May 2017.

Key Notes:

  • Google products have over one million active users.
  • Google photos users upload 1.2 billion photos daily.
  • Google maps users navigate over one billion miles per day.
  • Android now has over two billion active devices.
  • YouTube viewers view over one billion hours of video per day.


  • Google Lens
    • It’s a set of vision-based computer capabilities that will show up on Google Photos and Google Assistant first.
  • Google Assistant available on iPhone
  • Google Assistant SDK allows any manufacturer to include assistant in virtually any smart phone.
    • That includes drink mixers, refrigerators, washing machines, or whatever
  • This summer, Google Home (Voice-activated speaker) will be launched in Canada, Australia, France, Germany, and Japan.
  • Google Photos will soon be able to remove obstructions from photos.
    • For instance, it can remove a fence if you want to just have the image behind the fence.
  •  YouTube will begin to support 360-degree video (including live video) on television
  • Kotlin will be an officially supported language in Android. It’s a new programming language.
  • Google announced Android Go.
    • It optimizes the latest Android releases to run on low end phones.
  • Google announced that standalone VR (Virtual Reality) headsets are coming.
    • It’ll be an Android powered device made specifically for a VR experience.
    • Partners include Qualcomm, HTC, and Lenovo.
    • Devices will come to market later this year.

Redundant Array of Independent Disk (RAID)


The Term “RAID” was used in 1987 by David Patterson, Garth A. Gibson and Randy Katz at the University of California, Berkeley in 1987.  In their 1988 report, “A Case for Redundant Arrays of Inexpensive Disks (RAID)” they argued that the mainframe disk drives performance can be beaten by RAID. By configuring redundancy, the reliability is beyond to any extent single drive.


The term RAID related to hard disk management technique mostly for server side.  RAID is a data storage virtualization technology that combine multiple hard disk into a single logical unit for data redundancy, reliability and performance improvement.  It has used mirroring, stripping and/or parity to achieve the RAID configuration.  Once the RAID is setup, it forms a single logical disk for the operating system.


In Stripping, hard disk divided into blocks and these blocks are stacked together and called strips. With multiple hard disks placed parallel or serial, we can achieve the stripe. Without mirroring and parity, Stripping cannot have safe data but stripping may significantly improve the I/O performance.



Mirroring is most trusted method for data protection in RAID.  This is straightforward way to understand as it copies identical data onto more than one drive in real time. It most commonly used in RAID 1. In case the first disk failure, the controller uses the second disk to serve the date, and it makes the data available continuously without any disruption.

When the failed disk is replaced with a new disk, the controller copies the data from the surviving disk of the mirrored pair. Data is simultaneously recorded on both the disk. Though this type of RAID gives you highest availability of data but it is costly as it requires double amount of disk space and thus increasing the cost.



This is reliable and low-cost solution in RAID for data protection. In this method, an additional disk is added to stripe width to hold parity bit.  Parity used for fault tolerance by calculating the data in two drives and storing results on third drive.  RAID 3 used parity disk for fault tolerance and fast data stripping.

The parity bits are used to recreate the data during the disk failure.  Parity information can be stored a separate disk or can be stored across all disks.


RAID Controllers

A RAID controller is a hardware or software program used to manage the hard disks in storage array so that they can be as a logical unit.  RAID controllers bridge between the operating system and the hard disks.

In hardware-based RAID, physical controller is used at motherboard or at separate RAID card to present the data to the applications and operating systems as logical units. The controller resides on a PCI bus.

In Software RAID performs the processing on the host’s CPU.  Thus, it gives a cheapest possible solution.  The difference between the hardware RAID and software RAID is where the RAID processing happens. Software-based RAID does not use the server processor and hardware-based RAID provides better performance. Hardware-based RAID is more expensive than software based RAID due to its additional hardware.


Standard RAID levels


RAID 0 knows as stripping.  Data split and stored across two or more disks, without any parity, redundancy or fault tolerance.  Since RAID 0 has no fault tolerance, the failure of one disk will cause the entire array to fail.

  • Minimum 2 disks.
  • No redundancy
  • Do not use for mission critical applications.




In RAID 1, data is writing simultaneously in two disks. It consists of exact set of data (mirror) on two or more disks.  If one disk failed, the data can be retrieved from the other disk.

This layout is useful when read performance or reliability is more important than write performance or the resulting data storage capacity.

  • Minimum 2 disks.
  • Excellent redundancy
  • Good performance
  • Do not use for mission critical applications.




RAID 2 is rarely used in practice, it stripes data at the bit level rather than block level. It uses a hamming code for error connection.








RAID 3 also rarely used in practice, it stripes data at the byte level with a dedicated parity disk.  RAID 3 cannot serve multiple request simultaneously.







RAID 4 stripes data at the block level with a dedicated parity disk. RAID 4 provides superior performance of random reads, while the performance of random writes is low due to the need to write all parity data to a single disk.







RAID 5 consist of block level stripping with distributed parity. In RAID 4 parity information is distributed among the disks. It requires that all drives but one be present to operate.

Upon failure of a single drive, subsequent reads can be calculated from the distributed parity such that no data is lost.

  • Minimum 3 disks.
  • Good redundancy
  • Good performance
  • Use for databases that is heavily read oriented. Write operation is slow.



RAID 10 also known as RAID 1+0. It combined disk mirroring and disk stripping to protect the data. If one disk in each mirrored pair is functional, data can be retrieved.


  • Minimum 4 disks.
  • Excellent redundancy
  • Excellent performance
  • Best option for mission critical applications especially databases.




Ransomware Cyber Attack

What is Ransomware?
Ransomware is a cyber attack by wannacry malware for those computers are connected to the internet. This is mainly targeted on Microsoft Windows Operating Systems by encrypting the user files in a way that can’t access it anymore and demanding some money in the Bitcon crypto currency. The attack was beginning on 12th May 2017 and affected many companies like British hospital and Spanish companies like Telefonica etc. This worm has attacked over 200,000 computers in 150 countries.

How it affects?

Email link and email attachment account for 59% of Ransomware attack. Users are more prone by clicking the links than accessing an infected website.  Attackers send the wannacry worm emails to users to ask them to click or download the attached file. When user click the link, or download the files from emails the worm enter the computer.Email link and email attachment account for 59% of Ransomware attack. Users are more prone by clicking the links than accessing an infected website.  Attackers send the wannacry worm emails to users to ask them to click or download the attached file. When user click the link, or download the files from emails the worm enter the computer.

Wannacry malicious ransomware worm targets computers are running Microsoft windows operating systems. Wannacry spread by using EternalBlue, an exploit of Windows SMB (Server Message Block) Protocol.  It installs the DoublePulsar, a backdoor implant tool, which then transfers and runs the Wannacry ransomware package. Once the package installed it will encrypt all data by converting that .crypt file format, when try to open the file, it redirect to the payment option. Also, it scans the vulnerable systems then use the EtenalBlue an exploit to gain access and spread itself to the computer network and affect all files.

Security experts warns that there will be no guarantee that the access will be granted after payment.

How to prevent it?

  • The first option is try not to click the email link which is send by unknown person. Also try not to download any documents from unknown person.
  • Update your Operating System updates from Microsoft.
  • Ensure your network firewall and antivirus software is up to date.
  • Those are using Office 365, subscribe Work Plus ATP (Advance Threat Protection) from Microsoft.
  • Do regular backup of your working files and keep in separate place which is not connected to your current network.
  • Ensure your email server provide spam filter is working good.
  • Discovered ‘kill switch’ for Ransomware attack. It slows down the wannacry malware spread
  • Microsoft issued critical security patch on 14 March 2017 to remove the underlying vulnerability on supported versions of Windows.

NAT & Double NAT


There are 4 billion IP addresses are available in IPv4 (32 bits) network. If each person connect to the internet using individual IP address, the current IP addresses in IPv4 (4,294,967,296) is not enough. Network Address Translation (NAT) concept was introduced to solved this IP address issue.  The router get only one public IP address from ISP and all other connected devices gets the private IP address, it usually start with 192.168.0 or 10.0.0.  NAT converts all private IP address request and send outside the world using one public IP address.  With this, a home or an organization needs only one public address to connect the internet. Router are distributing private IP addresses using DHCP function.


Double NAT means multiple devices on the network are performing NAT functions. Example for this is, WiFi Routers are connected with the ISP Modem / Routers. It won’t prevent you to connect the internet, but sometimes it will create issues for VPN connections, accessing SSL websites, online games, and accessing other private network.

Solutions for Double NAT:

  • Enable Bridge mode in wireless router
    • Login to wireless router admin page in web-browser
    • Settings page, enable the bridge mode or disbale NAT and DHCP functions.
  • Set wireless router in modem’s DMZ
    • Login to wireless router admin page and find the WAN IP Address
    • Login to modem and go to DMZ settings.
    • Add wireless router, WAN IP address in DMZ settings.
  • Setup PPPoE between modem and wireless router
    • set PPPoE in wireless router.
    • PPPoE will bypass the NAT in the modem.

Router’s common issues

Routers are mandatory for small businesses and homes to connect the outside world.  Wireless routers are common for home and all types of businesses to get the internet connection to their desktops, laptops, smart phones, tablet devices and other wireless devices. Router determines how to send and where to send the information from one computer to another computer.  The information can be send from one network to another network as well.

Common issues of routers are:

  • Difficult configurations
  • Firmware updates
  • Hardware specs (Memory, HDD etc)
  • no. of simultaneous users

Common issues of Wireless routers are :

  • Interference (Positioning of router).
  • Distance between Wireless Access Points and client devices.
  • Router capacity for concurrent users.

Best ADSL Router

TP Link AC1750 Wireless Dual Band Gigabit ADSL2+ Modem RouterArcher D7

  • Supports Superfast Wireless Speed with 802.11ac standard
  • Dual band
  • 3 dual band detachable external antennas
  • Full Gigabit Wired Connection
  • One Gigabit LAN/WAN port
  • Three Gigabit LAN ports
  • Simultaneous 2.4GHz 450Mbps and 5GHz 1300Mbps connections provide a premium wireless experience
  • Share a printer locally and files & media with networked devices or remotely via FTP server
  • Ethernet WAN (EWAN) port accepts connections from cable and fiber modems via Ethernet cable
  • TP-LINK Tether provides the easiest way to access and manage the router on your iOS and Android devices