The History Of Domain Name System

Published Date: 02 Nov 2017

The Sidebar is a prominent feature of Google Desktop. It holds many of the installed gadgets and can be seen on one side of the desktop. Below are the preinstalled gadgets.

- Email

- Photos

- Web Clips

- Google talk

Privacy Concerns

Google Desktop has a feature that able to search my desktop remotely. If this feature is turned on, the files on the indexed computer are copied onto Google servers thus increasing the chances that my information will be accessed without my permission.

Google Toolbar

Google Toolbar is an Internet toolbar that is available for Mozilla Firefox and Internet Explorer. It has a search area that allow user to perform web searches. The toolbar can allow users to login to their Gmail accounts and access their email and saved bookmarks. It also have features like AutoFill, translating mechanism (translate entire webpages) and popup blocker.

Privacy Concerns

Google Watch has raised some privacy concerns of installing the Google Toolbar, such as tracking browsing patterns, automatically updating the client without notice and privacy policy can change without mention. The toolbar does not track personally identifiable browsing activities unless more advanced features are turned on by the user, like the PageRank service.

b)

Google Chrome

Google Chrome is a web browser that is developed by Google. First released in September 2008, it is a popular web browser worldwide. The web browser Chrome is part of an open-source project called Chromium.

Chrome aims to be fast, secure, stable and simple. Chrome periodically receives and updates two lists, one list for phishing and the second one for malware. It uses these lists to warn the user when they are access to a harmful website. Chrome able to allocates a separate process to each tab and prevents malware from installing itself and also prevents the activities in one tab from affecting activities in another.

c)

Google Mail

Google Mail (Gmail) is a free web email service provided by Google. Google provides over 11000 megabytes of free storage for emails. An additional storage can be rented for a yearly fee depending on the size. The Gmail interface focuses on its search and an appropriately named ‘conversation view' of emails. It groups all the replies to an email on a single page to make it feel like an email conversation. Gmail has an in-built community driven spam filter. For example, when a user marks a message as spam, it helps the system identify similar messages for all Gmail users. Gmail also has an integrated chatting facility.

Privacy Concerns

Google automatically scans emails and adds advertisements that are content-sensitive to them. Furthermore, Google can scan the content of an email and this information can be linked to Internet searches made from the Google.com website. Such information can potentially be used by law enforcement agencies.

d)

Google Apps

Google Apps is a service provided by Google that has customizable versions of several Google products. It features many web applications including Gmail, Google Groups, Google Docs and Google Talk. Google Apps comes in three editions:

- Google Apps for Government

- Google Apps for Business features additional email storage and is available for a fee payable annually

- Google Apps for Education.

e)

Google AdWords

AdWords is Google's main advertising product, also a primary source of revenue. AdWords have following three types of advertising:

- Pay-per-click: advertisers choose the words that will activate their advertisements and the maximum amount of money that they will pay Google per click. The ads that are triggered by this process appear as ‘Sponsored Links' at the right of the search results page.

- Cost-per-thousand

- Site-targeted advertising for text, banner, and rich-media ads.

Two prominent features of AdWords as below:

- IP address exclusion: This allows advertisers to specify a range of IP addresses where they do not want the ads to appear. Maximum 20 IP addresses can be used in this feature.

- Frequency Capping: This feature limits the number of times a particular ad appears for a unique user.

Now a day, a lot of companies would like to create a web site to let peoples know their company and products through Internet. Some Small Medium Business, especially whole sale business. They might not have a lot of money can spent to produce some advertisement on TV, newspaper or public transportation. They may also have not build up a well computer infrastructure inside the company so that no their own email server can be use. Like this kind of companies, Google’s features are very useful for them. Firstly, Google mail can help these companies able to have email to use for free without an own mail server. Secondly, Google Adwords can help them to put some advertisement on the web cheaply to let peoples know their company and products. Thirdly, Google Apps able to help the staffs of these companies can work more efficiency.

Task 2

a)

Domain Name System (DNS)

The Domain Name System (DNS) is a system that assigns names to computers, services or any other resource that connects to the Internet or private network. It translates alpha-numeric characters used by networking equipment for locating and addressing these devices. This resolving of names follows below steps:

- A host is configured with an initial cache of a known DNS server

- If the known DNS server does not contain the information the host requires, it queries the root DNS server

- The root server responds with the relevant top-level domain (TLD) server

- The TLD server is queried for the second-level domain server

- The process is repeated until the domain name is found.

Internet Protocol (IP) address

An IP address is designed to allow a digital device to communicate with another through the Internet. IP addresses make the devices that are connected to the Internet to be pinpointed and differentiated from other devices.

Internet Protocol version 4

Internet Protocol version 4 (IPv4) is the fourth revision of the Internet Protocol (IP). IPv4 is a connection-less protocol, It does not guarantee the packets will be delivered, in a proper sequence or prevent duplication.

IPv4 uses a 32-bit addressing scheme, which limits the addressing space to 232 (approximately 4.3 billion) unique addresses. Some of addresses are reserved for special purposes, such as private networks or for multi-cast addressing. This reservation reduces the number of available IPs or public IPs that can use over the Internet. Due to the demand for IP addresses has been increasing rapidly with the growth. So that the IPv4 address has been becomes not enough for use.

A variety of technologies have been developed to delay the depletion of the addresses, such as below:

- Network Address Translation (NAT)

- Use of private networks

- Use of Dynamic Host Configuration Protocol (DHCP) server

DNS name server

A DNS server runs special-purpose networking software that has an IP address, and contains a database of network names and addresses for other hosts.

Resolver

Also called DNS resolvers. Resolvers are the names given to computers that used to respond to a user request to resolve a domain name. These computers translate a domain name into an IP address.

DNS Infrastructure

The DNS infrastructure consists of DNS servers that run the DNS Server service and DNS clients that run the DNS Client service.

Fully qualified domain name (FQDN)

A fully qualified domain name (FQDN) is the complete domain name for a specific host. The FQDN include the hostname and the domain name. i.e. www.google.com is the FQDN on the web. In this case, www is the name of the host in the google.com domain.

Network ID

A Network ID is a term used to describe the basic part of a network. If 192.168.1.0 is a Network ID and the Subnet Mask of 255.255.255.0, the network is 254 usable addresses. Since 192.168.1.0 is the first number so that is not a valid addressable IP address and 192.168.0.255 is the network's broadcast address.

Subnet mask

A Subnet Mask is a number. It is determined using binary from 0.0.0.0 to 255.255.255.255. Subnet Mask defines a range of IP addresses that can be used in a network. Subnet masks are used to define subnets. Systems are able to communicate directly with each other if they are within the same subnet. However, systems are on different subnets that must communicate through a router. Thus, subnetworks can be used to partition multiple networks and limit the traffic between them.

b)

Below are the common vulnerabilities in Domain Name Servers (DNS)

Can gain root-level access to name server by a remote intruder.

The normal operation of name server may disrupt by a remote intruder.

The DNS protocol in BIND 8 and 9 allow remote attackers to spoof DNS traffic thought cache poisoning techniques.

A cryptographic weakness in the generation of DNS query IDs could expose the DNS server to a cache poisoning attack. Only outgoing queries of Bind 9 would affected by this bug to answer questions as a resolver or when it is looking up data for internal uses, i.e. when sending NOTIFYs to slave name servers.

c)

Measures can be taken to secure DNS-

Used only secure dynamic updates option for dynamic update to protect DNS servers from spoofing of DNS records.

Use firewall to block the unused ports to prevent exploitation of remote vulnerabilities (i.e. RPC vulnerabilities).

Should be providing separate views of DNS for internal users and external customers If an organization has an intranet.

d) i)

I need to design a network that with 1000-1500 PCs. So I would like to use Class B IP address. It is because Class B IPs supports 65000 hosts over 16000 networks.

ii)

I used www.checkdomain.com to check the availability of a domain – chrischk.com.

The result showed that this domain is available.

iii)

Subnets design.

iv)

Description of the range of TWO subnets IP address as following:

For subnet R - 10.153.4.64 is the first number and the network ID of its subnet. It is a class B IP address. The host IP starts from 10.153.4.65 to 10.153.4.126. 62 PCs here can establish a sub network. The broadcast address of this subnet is 10.153.4.127.

For subnet P – 10.153.3.192 is the first number and the network ID of its subnet. It is a class B IP address. The host IP starts from 10.153.3.193 to 10.153.3.254. 62 PCs here can establish a Sub network. This broadcast address of this subnet is 10.153.3.255.

Task 3

a)

b)

#!/usr/bin/perl

print "Content-type: text/html\n\n";

print "<html>\n";

print "<head>\n";

print "<title>\n";

print "Internet Systems Administration assignment, Task 3\n";

print "</title>\n";

print "</head>\n";

print "<body>\n";

print "This is a simple HTML page.\n";

print "</body>\n";

print "</html>\n";

c)

d)

e)

The POST Method

POST is one of the many request methods supported by the HTTP protocol on the Internet. The POST method is used when a client needs to send data to the server, like when uploading a file or completing and submitting a form. It is part of the request body. The server receiving the data will usually send it to a CGI program along with other variables that are required for processing.

Advantages

- There is no limit to the number of characters that can be sent to the server using the method; the administrator sets this limit manually. Therefore large amounts of data can be sent through

- Data that is passed using this method are hidden in the browser, making it suitable for sending sensitive data like passwords.

Disadvantages

- The users cannot bookmark or have direct access to such pages; they will need to re-enter the information through the form to access the page

- Because these pages cannot be accessed without entering data into a form, search engines cannot index them.

The GET Method

This method is used to retrieve web pages from the server. It is part of the client request line and tells the server to pass the document to the client browser or run a CGI program.

Advantages

- Unlike pages generated using the POST method, users can bookmark pages that are generated using GET. This means that data does not need to be re-entered into a form

- Search engines can index these pages

Disadvantages

- The number of characters passed is limited, which means that it is not suitable for sending large amounts of data to the server

- The data sent is visible in the browser, making it unsuitable for sending sensitive data such as passwords.

Task 4

a)

Peer-to-Peer Networking

Peer-to-Peer (P2P) is a networking architecture that does not have a central computer or server for management. PSP divides the workload between peers. Peers (also call nodes) are both consumers and suppliers of resources such as disk storage and processing power.

In a P2P network, all nodes have equal rights, importance and priority, There are no nodes that perform a special function. All of them act as clients and servers simultaneously. The clients provide the resources to the network, which may include bandwidth, storage space and even processing power. When a new node is added onto the network, the total capacity will increases due to there are more clients providing resources at the same time.

There are many applications of P2P networking on the Internet, such as DNS, cloud computing, VoIP services. The most popular use of P2P networks is file sharing. Many file-sharing networks exist like BT was the ones that increased bandwidth utilization over the Internet.

Client-server Networking

The Client-server networking model is one that is prominently used. Clients send requests for resources to a server(s) and the server replies with that resource. Clients send requests to the servers by using only one way so that the servers no need to initiate the communication. ‘Client' and ‘server' can refer to a computer system or an application. Servers usually run on dedicated machines and are long-running applications. Clients are usually laptops, desktops and hand-held devices. Client-server systems are based on resources and resource identifiers.

For Internet, World Wide Web is one of the applications which using Client-server Networking. The main resource is the webpage, using URL to identify it. The client (web browser) requests for the webpage using URL and the server (web server) sends information on how to display the page back to the browser.

b)

Two well-known applications of the client-server architecture

FTP

FTP (File Transfer Protocol) is use to transfer data between computers on the network easily and faster. FTP transfers data between server and client. When you want to transfer data with FTP, you can simply use a web browser to download only or use FTP client to upload or download files on FTP server. And FTP can setup to request client to input username and password to login for verification.

Email

Email (Electronic mail) is one of the most popular uses of the Internet. Once you have an e-mail account you can send an electronic message to anyone else with an e-mail account. The salient features of e-mail are as below.

• Delay message sending and offline mail reading

• Automatic mail forwarding and mail checking

• Mail filters and automated mail processing

• File attachment and flexible formats

E-mail work as a store forward system so there is always a delay between the time of a message is sent and time it arrives. It is not a live connection between the sender and its recipients. E-mail system has two different protocol. Theses two protocols are SMTP and POP. SMTP stands for simple mail transfer protocol. It is used for handling outgoing mail. The POP stands for Post Office Protocol. It is used for handling incoming mail.

One example each for four main categories of the P2P architecture

Communication and Collaboration

Instant messaging (IM) allows two or more of users to carry on the fast and direct exchange, it let you found your friend or job partner on the network easily and faster. Beside, a lot of IM software integrated data interchange, voice-enabled chat, network meeting and email function. MSN is one of the most popular used of Instant messaging software.

File sharing

Bit Torrent is file sharing application that is faster and more widely used P2P architecture. BT‘s has a better performance than other P2P program. However, it is easily to infect virus like Trojan Horses or malware.

Platform

Juxta-CAT is use the JXTA architecture to build a job execution-sharing distributed environment. The goal of this platform is giving direct access to resources and sharing of the computing resources of nodes. Other well-known P2P systems that only share hard disk contents.

Distributed computing

SETI@Home is one of the P2P distributed computing applications. P2P distributed computing through the coordinated use of the peer entity outside the computing power to solve large computational problems, such as space exploration and molecular biological computing. It is the sharing of the CPU resources on the network essentially.

c)

Comparison between client/server and p2p Network:

Advantages of p2p network:

Less initial expense - No need for a dedicated server.

Setup - An Windows XP operating system already in place

Disadvantages of p2p network:

Decentralized - No central repository for applications and files.

Security - Does not provide the security that available on a client/server network.

Advantages of client/server network:

Centralized - Resources and data security are controlled through the server.

Flexibility - New technology can be easily deployed into the system.

Accessibility - Server can be remote access cross multiple platforms.

Disadvantages of client/server network:

Expense - Requires initial cost in dedicated server.

Maintenance - Large networks will require more than one staff to ensure the operation.

Dependence - Operations will cease across the network when server goes down,

Words Count

Introduction 47 words

Task 1 84 words

Task 2 259 words

Task 3 7 words

Task 4 447 words

Total 1883 words