Addressing in ipv4 : part 1 (Lesson: 6)

Addressing in ipv4 (part 1)

Overview

In the previous chapter, we looked at the network layer and its involvement in communication. in this chapter, we will look at ipv4 addressing. This is one of the most important concepts in networking and will be critical in your overall success in networking. Understanding this chapter is critical to the rest of your studies. This chapter is divided into two parts so that it can better understood. In the first part, we will look at binary vs decimal, then we will be introduced to subnetting. Then we will finish up by subnetting a few addresses.

Decimal vs binary

We are used to decimals. The number systems used everywhere today is mostly binary. Base of 10.

10^0=1
10^1=10
10^2=100

This is what we use in day to day activities. However, computers are limited to only 2 digits. “1” and “0”, which represent “ON” and “OFF”. The ip addressing system we use is based on this concept. All ipv4 addresses that we use are a decimal representation of the binary form that the computer knows about.

The table below shows the difference between decimal and binary connotations.

You will be seeing the binary table more frequently as we continue in this chapter and others.

How networks are addressed

I believe the most of you have seen an ip address. The ip addressing scheme used contains two parts.

• The network part – from the left hand side
• The host part – from the right hand side

In IPv4 addresses, the high-order bits (bits starting from the left side) represent the network address, the low-order bits (bits on the right hand side) represent the host portion. In IPv4 addressing, hosts who have matching high-order bits are said to be in the same network.

Windows Ink: How to use Sketch pad

Windows Ink: How to use Sketch pad

Sketch pad is a new feature available in the Windows 10 Anniversary Update, part of the new Windows Ink Workspace feature-set. It allows tablet users to doodle, take notes and more directly on their tablets in a dedicated inking environment, equipped with virtual rulers, pen-types and more. Here's how to use it.

How to open Sketch pad

1. Tap the Pen icon on the taskbar to open the Ink Workspace.

2. Tap the "Sketch pad" feature when Ink Workspace is open. It will be the second block in the list. You'll be greeted with a white canvas.

Network layer (Lesson: 5)

Network layer

Overview

In the previous chapter, we looked at the role of the OSI transport layer in communication. In this chapter, we will look at the network layer. We will discuss the addressing used, the functions, and the different network layer protocols, introduce IPv4, understand how packets move in the network and finally give an overview in how we address the network using IPv4. You should be able to understand these concepts as they will be used in the chapter on addressing in IPv4 as well as in subsequent chapters.

Introduction

The network layer defines communication over the network through four basic processes which are addressing, routing, encapsulation and decapsulation. These concepts are vital in understanding routing.

Addressing

You may have sent a letter through the post office, while doing this, you are required to write the address of the recipient on the envelope and most likely your address for reply purposes.

In the same manner, the network layer is responsible for identifying the various devices in the network. However, unlike the postal addresses, addressing in the network layer is logical. This means that addresses are not fixed to the devices and they may change.

The addresses that are used in this layer are for remote delivery, if we use the post office analogy, remote delivery would be sending a letter to another organization. Local delivery – which will be discussed in a later chapter can be likened to sending a note to a colleague who is seated next to you.

Encapsulation

The network layer PDU- protocol Data Unit is the packet. Encapsulation entails adding layer 3 specific information based on the segments from the transport layer. Such information includes headers and trailers. It also divides the segments from the transport layer for remote delivery.

The Echo doesn’t have one killer app, so Amazon is creating Alexa gadgets for every use case

The Echo doesn’t have one killer app, so Amazon is creating Alexa gadgets for every use case

Amazon on Wednesday announced five new Alexa-powered Echo devices in a dizzying product rollout that comes across as either impressively ambitious or insane and unfocused.

There was an upgrade to the original Echo that is smaller and cheaper at $100; a touchscreen Alexa-powered alarm clock called the Echo Spot for $130; and the Echo Plus with a smart-home hub embedded in it for $150. Then there were tiny Echo Buttons to be used for trivia or games at $20 a pop, and even a $35 Echo Connect gadget to turn your home phone line into an Alexa-powered speaker phone.

Add the existing Echo Dot, Echo Show, Echo Tap and Echo Look to that portfolio, and that gives Amazon nine different Echo gadgets in a little more than two years.

Alexa, what’s up with that strategy?

One theory — well, my theory: Amazon hasn’t found one, single, no-brainer use case for the Echo, so it’s releasing different form factors that can push different behavior.

The Echo Look is designed specifically for fashion advice. The Echo Show and new Echo Spot have touchscreens, making them well suited for video calls and video clips.

There’s also the new Echo Plus, which is built to be a hub to a smart home, making it easier for consumers to use voice commands to control in-home systems like lighting or heating. And the new $100 flagship Echo, which comes with improved sound that may make it a popular choice for those who prioritize music streaming over other Alexa features.

You get the idea.

The beauty of Alexa is that all of these devices come with the same brain that can offer many of the same experiences. But tweaks to the body that sits around the brain — the hardware — can produce different behavior.

Amazon may find enough people that see value in enough different use cases for all of these different devices to succeed. But, more likely, some new Echos will drive use cases that become way more popular than others, helping Amazon to focus more on fewer variations over the long-term.
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iOS 11 Update Fixes Bugs, Email Support for Outlook Users

iOS 11 Update Fixes Bugs, Email Support for Outlook Users

Image credit: Justin Sullivan/Getty

Having some trouble sending an office email on your iPhone? You downloaded iOS 11, didn’t you. Sure, it’s got some dope upgrades inside, but it’s also the first version of the new operating system, and that means bugs. True to form, a software issue in iOS 11 is preventing Exchange email servers from sending and receiving messages, affecting Outlook, Office 365, and Exchange Server 2016 users. The good news is that Apple’s latest iOS update, 11.0.1 fixes the issue, along with some other unspecified bugs.

Users of the Microsoft-hosted email services were greeted with the message “Cannot Send Mail. The message was rejected by the server” after downloading the first version of the new iOS. Not a great feeling, to be sure. Apple has since addressed the issue in a support page, where it tells users to upgrade to iOS 11.0.1. We generally recommend performing software updates through iTunes and a wired connection, but visiting Settings > General > Software Update will also let you update the OS from your device.

While it probably did fix a few bugs, and Outlook and Exchange users can send emails again, iOS 11 still feels a bit unpolished. App rearranging is a buggy affair, and essential shortcuts in the updated Control Center aren’t as useful as they once were. If you’ve been holding out until the first bug-fixing update, then go right ahead and upgrade your device. Just check to see if it’s compatible first. Don’t want you to get your hopes up.
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