What is meant by DNS? What does it contain?

DNS or domain name system is a well known distributed system which is quite hierarchical in nature and is used for the following:

1. Computers
2. Services
3. Resources that are connected to some private network or internet and so on.

What does DNS contain?

- With the aid of DNS, the domain names with various participating entities contains various information. 

- A domain name system is also known as domain name service and has taken up the responsibility of resolving the queries for the above discussed domain names into the corresponding IP addresses. 

- The basic purpose of this whole process is spotting the location of devices and computer services on the World Wide Web.

- The domain name system had lately become quite an essential part of the functionality of the internet because of the world wide service it provides regarding the distributed key word based redirection. 

- To put it simply it acts as a phone book in disguise for the internet. 

- It serves as a phone book in the way that it translates the human friendly computer host names in to their corresponding IP addresses. 

For example,

The domain name: www. Abc. Com translates in to the following IP address (say): 192. 0 . 34 . 11 (IPv4) and 2630 : 0 : 2c0 : 201 : : 10 (IPv6) etc.

- Though DNS serves all the purposes of an ideal phone book in terms of the internet, it differs from the phone book in one respect which is that the DNS can be frequently updated and these updates in turn can be distributed but in phone book these tasks cannot be performed so.

- With the help of such a process the location of a particular service on a network can be easily changed without having any affect on the end users who keep on continuing with the same host name. 

-This advantage is further reaped by the users while they recite the meaningful e- mail addresses as well as the URLs (uniform resource locators) without even knowing the way via which the services are actually located by the computers. 

- With the help of domain name system, each and every domain in the network is assigned with an appropriate domain name and this domain name is mapped to corresponding IP addresses through the designation of the authoritative name servers for each and every domain. 

- These authoritative name servers hold the responsibility of their particular domains and also it helps in assigning the sub domains with their respective authoritative name servers.

- Such a mechanism has helped a lot in making the domain name system quite fault tolerant and distributed. 

- This mechanism in another way has eliminated the requirement of a single central register to be used continually for updating and consultation. 

- There is one more additional feature of the domain name system which is that the responsibility of the updating and maintenance of the master record of the domains is distributed among many domain name registrars.

- These domain name registrars are known for their competition for the domain owner’s and end user’s business. 

- The facility of moving the domains from one registrar to another has been very well provided in the domain name system.

- The technical functionality of the data base service as well as the DNS specification is also specified by the domain name system.

- This DNS protocol is a kind of detailed specification of the communication exchanges and data structures that are used in the domain name system which in turn forms a very important part of the whole internet protocol suite. 

Explain how the data is secured in HTTPS?

HTTP secure or HTTPS can be thought of as an extended version of the regular HTTP. This communication protocol is the widely used one next to the regular HTTP when it comes to having a secure communication path between the user and the server over a computer network. 

The HTTPS finds quite a wide deployment over the internet when compared to deployment over intranet. If we understand it deeply we will come to know that in actual it is not a protocol in itself as it seems so from outside. 

It is actually a regular hyper text transfer protocol (HTTP) simply layered over SSL/ TSL protocol. The SSL/ TSL protocol thus lends its security capabilities to the standard HTTP communications when HTTP is layered up on SSL/ TSL. 

In this article we discuss how the data is secured in HTTPS. As we mentioned above that it is quite deployed in the internet services and it is so because it provides a quite convenient means to authenticate the web site as well as the web server associated with it (with which the connection is being established).

How data is secured in HTTPS

Such an authentication is of much importance as it provides the protection against the man in middle attacks which usually occurs because of eavesdropping between our communications with the server. 

- Moreover, HTTPS provides bidirectional encryption of the communications or the data that is exchanged between the clients and the servers. 

- The ability of the bidirectional encryption by virtue of which it protects against tampering and eavesdropping which otherwise would forge the contents of the communications between the clients and the servers, makes it much necessary. 

- HTTPS comes with a reasonable guarantee that you get to communicate only with the web site which you intended to communicate with and with none else.  - Furthermore, a way to prevent the forgery of the contents of the communication that takes place between the users and the clients cannot be hampered or forged by any of the third parties is ensured by the http secure. 

- In HTTPS, the entire HTTP is levied up on the top of the TSL or SSL thus enabling the total encryption of the HTTP communications content.

- This communications content includes:

1. Request URL which states the particular web page that was requested.
2. Query parameters
3. Headers
4. Cookies containing the identity information about the user and so on. 

Negative Points of HTTPS

Though the HTTPS has got many advantages, its minus point cannot be unseen.

-HTTPS cannot protect the disclosure of the communication content.

-This happens so because the addresses of the host web sites and port numbers form a necessary part of the TCP/ IP protocols that underlie the https. -To be seen practically, it means that the identity of the server can still be inferred by the eavesdroppers even on a correctly configured web server as well as the amount and duration of the communication.

-In the early years, the HTTPS was common to be used in the money transactions over the World Wide Web and other sensitive transitions like e- mails.

-In the recent years it has been known for the following:

1. Authenticating the web pages,
2. Providing security to the accounts,
3. Maintaining the privacy of the user communications, web browsing and identity.

The HTTPS has also come to the rescue of the wi- fi since it is highly prone to attacks being un- encrypted. The importance of https is often more realized when the connections are made over tor or anonymity network.       

What are the differences between testing WEB application and testing client-sever application?

Web application as we know are the kind of applications that can be accessed by one over a computer or internet or intranet network. Some of the web applications are also coded in to the web browser via web browser supported language like HTML or JavaScript. 

There are so many reasons that make web application quite famous with its users like:

1. Because of web browsers’ ubiquity.
2. Because web applications provide a means to use web browsers as a client that are usually termed as thin clients.
3. Because they can be updated and maintained without having to disturb and install the software system or application on 1000s of client systems.
4. And also because they support cross platform compatibility.

Now that we have discussed regarding the web applications, let us see what client server applications are! 

- A client server application is actually not an application rather it is a computing model that acts like a distributed application whose purpose is to partition the work loads or the tasks among the resource or service providers that are merely servers and clients (the service requester).

- The communication among the server and the client is established over a computer network and in most of the cases the servers as well as the client reside in the same system.  

In this article we are going to discuss the differences between testing the two types of the above mentioned applications. It is very necessary to test these applications since our personal as well as commercial needs are much dependent on these. 

First we will be talking about web application testing and then later regarding client server application testing so that the differences between the two will be clear to you! 

About Web Application Testing

- Web application testing is a combo of the following types of testings:

1. Usability testing
2. Compatibility testing
3. Security testing
4. Performance testing
5. Interface testing and
6. Functionality testing

- All these above mentioned tests make up a complete testing path for web applications. 

- These two types of testing i.e., the web application testing and testing client server application, differ on the basis of the environment in which they are carried out. 

- Testing a web application proves to be more difficult when compared to testing a web client server application and is quite complex too! This is so because the testers do not hold much control over the web application under question. 

- In web application testing, the application to be tested is loaded on a server whose location either or not may be known to the testers. 

- The .exe file is not installed on the client side and therefore it is to be tested on different web browsers. 

- Web applications are mostly tested for their compatibility with different OS platforms, error handling, back end testing, and load testing and static pages. 

About Client Server Testing

- Client server application testing is quite simple as compared to the web application testing and basically involves testing of two components.

- Here, like the web application testing is loaded on the server machine but unlike the web application testing, the exe file is installed on all the client machines. 

- The testing here is carried out broadly in categories mentioned below:

1. GUI on both the sides.
2. Functionality
3. Client server interaction
4. Functionality
5. Back end testing and so on.

- The kind of environment that is used in client server application testing is pretty much like the one that is found in intranet networks. 

- The testing team knows all about the location of the servers in the test scenario. 

SOAP (Simple Object Access Protocol) Protocol

SOAP stands for Simple Object Access Protocol. It is a communication protocol. It is for communication between applications. SOAP is a format for sending messages. It communicates via Internet. SOAP is platform independent and language independent protocol. SOAP is based on XML. It is simple and extensible protocol. SOAP allows you to get around firewalls. SOAP is a W3C recommendation.

SOAP is a protocol specification for invoking methods on servers, services, components and objects. A SOAP message may need to be transmitted together with attachments of various sorts, ranging from facsimile images of legal documents to engineering drawings. Such data are often in some binary format. SOAP consists of three parts:
- The SOAP envelope construct defines an overall framework for expressing what is in a message; who should deal with it, and whether it is optional or mandatory.
- The SOAP encoding rules defines a serialization mechanism that can be used to exchange instances of application-defined datatypes.
- The SOAP RPC representation defines a convention that can be used to represent remote procedure calls and responses.

Where is SOAP used ?

One of the most important uses of SOAP is to help enable XML Web Services. A web Service is an application provided as a service on the web. They are functional software components that can be accessed over the Internet. Web Services combines the best of component-based development and are based on Internet Standards that supports communication over the net.

Syntax Rules

A SOAP message must be encoded using XML. A SOAP message must use the SOAP Envelope namespace. A SOAP message must use the SOAP Encoding namespace. A SOAP message must not contain a DTD reference. A SOAP message must not contain XML Processing Instructions.

Message Format

XML was chosen as the standard message format because of its widespread use by major corporations and open source development efforts. The lengthy syntax of XML can be both a benefit and a drawback. While it promotes readability for humans, facilitates error detection, and avoids interoperability problems such as byte-order (Endianness), it can retard processing speed and be cumbersome.

FTP Software & Anonymous FTP Servers

FTP Software
Depending on what you are planning to do with your FTP software you should pick different ones. There are hundreds of free pieces of software so there is a very good choice. The three software packages are:

- Cute FTP : It used to be the best shareware FTP program around. It is easy to use and has many functions. Unfortunately, because it has become so popular, the latest version only allows you to transfer one file at a time unless you register. If you can find a copy of version 2.6.* it is an excellent program.

- FTP Explorer : It is not such a good program as Cute FTP but it is freeware so there are no annoying nag-screens. It can be downloaded here.

- Elite FTP : It is not such a good program for uploading standard files it works better if you are working with CGI as you can send commands to the server by typing them in.

Anonymous FTP Servers
A host that provides an FTP service may additionally provide anonymous FTP access. Users typically login to the service with an 'anonymous' account when prompted for user name. Although users are commonly asked to send their email address in lieu of a password, little to no verification is actually performed on the supplied data.
The login id for the public accounts on most anonymous FTP servers is anonymous, and guest is also common. The password can be anything, but most anonymous FTP service machines will ask you to enter your complete email address as your password.

Overview Of File Transfer Protocol

File Transfer Protocol (FTP) is a standard network protocol used to exchange and manipulate files over a TCP/IP based network, such as the Internet. FTP is built on a client-server architecture and utilizes separate control and data connections between the client and server applications.

The objectives of FTP are :
* To promote sharing of files (computer programs and/or data).
* To encourage indirect or implicit use of remote computers.
* To shield a user from variations in file storage systems among different hosts.
* To transfer data reliably, and efficiently.

What FTP does ?
It works by establishing a connection between one computer (for example, your PC) and another (for example, your Web server). To do this, you need to know the host name (e.g."webserver.example.com") or IP address (e.g. "12.34.56.78") of your Web server. Your FTP program will allow you to enter lots of different servers if you want (by host name or IP address), and usually you can double-click on one of them to connect to it.
- Logging in
Once connected, the Web server usually asks you for your user name and password.
- Transferring files
You're then logged in to your Web server. Once you're logged in, you can start moving files about. On most FTP programs, this works a lot like Windows Explorer or other similar file managers.
- The home directory
When you first log in, you will be viewing your home directory on your Web server. This will be the directory that contains your website, amongst other files.
- Going dotty
Some FTP programs will show two extra entries in the folder display - a single dot and a pair of dots. The single dot means "this directory" and usually does nothing, but the pair of dots mean "the directory above".