What is a Server?

Different Type of Servers

A server is a device with a particular set of programs or protocols that provide various services. Together, a server and its clients form a client/server network, which provides routing systems and centralized access to information, resources, stored data, etc.


At the most ground level, one can consider it as a technology solution that serves files, data, print, fax resources and multiple computers. The advanced server versions, like Windows Small Business Server 2003 R2 enable the user to handle the accounts and passwords, allow or limit the access to shared resources, automatically support the data and access the business information remotely. For example, a file server is a machine that maintains files and allows clients or users to upload and download files from it. Similarly, a web server hosts websites and allows users to access these websites.


 Clients mainly include computers, printers, faxes or other devices that can be connected to the server. By using a server, one can securely share files and resources like fax machines and printers. Hence, with a server network, employees can access the Internet or company e-mail simultaneously.


Server Plateform
Server is a word often used to describe the computing powerhouses behind a business’s network, website, applications and more. However, a server is an individual machine. Server platforms encompass multiple servers along with the operating system chosen to power the servers. The purpose of these platforms is to manage resources across a network, which vary based on a business’s needs.


Family of Servers and OS
Server platforms include all the hardware and software used to manage the network. Think of them as the brain and heart of a network. Whether you’re hosting the servers yourself or using a data center, you’ll use a family of servers which creates the platform.
It’s important to note that the term “servers” may not refer to multiple physical machines but can also refer to virtual machines. For instance, a single server may include multiple virtual servers with different purposes, such as applications, file storage and email.


Outside of the hardware itself, the most important component of server platforms is the operating system. The OS defines the types of tools a business has at their disposal to manage their network and overall business. The three most common systems behind server platforms include:

• Windows
• MacOS
• Linux

While MacOS isn’t used as widely as Windows and Linux, it’s a viable option for businesses switching mainly to Apple products and software. This ensures compatibility across all devices.
Windows and Linux are more widely used due to their versatility. Choosing the right one varies based on network needs, server hardware resources and required applications. Data centers and cloud services often offer a choice for your server OS.


Uncovering the differences isn’t always easy. Let the experts at ISOutsource provide you with unbiased opinions and facts to help you create the best server platforms for your business.Type of servers

TYPE OF SERVERS

Active Directory Server ?

Active Directory (AD) is a directory service for use in a Windows Server environment. It is a distributed, hierarchical database structure that shares infrastructure information for locating, securing, managing, and organizing computer and network resources including files, users, groups, peripherals and network devices.    Active Directory is Microsoft’s own directory service for use in Windows domain networks. It provides authentication and authorization functions, as well as providing a framework for other such services. The directory itself is an LDAP database that contains networked objects. Active Directory uses the Windows Server operating system.   When people talk about Active Directory, they typically mean Active Directory Domain Services, which provides full-scale, integrated authentication and authorization services.   Before Windows 2000, Microsoft’s authentication and authorization model required breaking down a network into domains, and then linking those domains with a complicated, and sometimes, unpredictable system of one- and two-way trusts. Active Directory was introduced in Windows 2000 as a way to provide directory services to larger more complex environments.   Other Active Directory services Over time, Microsoft has added additional services under the Active Directory banner.   Active Directory lightweight directory services This light version of Domain Services removes some complexity and advanced functionality to offer just the basic directory service functionality, without the use of domain controllers, forests or domains. Typically used in small, single office network environments.   Active Directory certificate services Certificate Services offers digital certification services and supports public key infrastructure, or PKI. This service can store, validate, create and revoke public key credentials used for encryption rather than generating keys externally or locally.   Active Directory federation services Provides a web-based, single sign-on authentication and authorization service primarily for use across organizations. Thus, a contractor might log on to his own network and be authorized for his/her access on the client’s network as well.   Active Directory rights management services This is a rights management services that breaks down authorization beyond an access granted or access denied model and limits what a user can do with particular files or documents. The rights and restrictions are attached to the document rather than the user. These rights are commonly used to prevent the printing, copying or taking a screenshot of a document.   Active Directory structure One key feature of Active Directory structure is delegated authorization and efficient replication. Each part of the AD organizational structure limits either authorization or replication to within that particular sub-part.   Forest The forest is the highest level of the organization hierarchy. A forest is a security boundary within an organization. A forest allows for delegation of authority to be segregated within a single environment. This provides for an administrator with full-access rights and permissions, but only to a specific subset of resources. It is possible to just use a single forest on a network. Forest information is stored on all domain controllers, in all domains, within the forest.   Tree A tree is a group of domains. The domains within a tree share the same root name space. While a tree shares a name space, trees are not limits on security or replication.   Domains Each forest contains a root domain. Additional domains can be used to create further partitions within a forest. The purpose of a domain is to break the directory into smaller pieces to control replication. A domain limits Active Directory replication to only the other domain controllers within the same domain. For example, an office in Oakland wouldn’t need to be replicating AD data from the office in Pittsburg. This saves bandwidth and limits damage from a security breach.   Each domain controller in a domain has an identical copy of that domain’s Active Directory database. This is kept up to date via constant replication.   While domains were used in the previous Windows-NT based model, and still do provide a security barrier, the recommendation is to not only use domains to control replication, but use organizational units (OUs) to group and limit security permissions instead.   Organizational units (OUs) An organizational unit provides for the grouping of authority over a subset of resources from a domain. An OU provides a security boundary on elevated privileges and authorization, but does not limit the replication of AD objects.   OUs are used to delegate control within functional groupings. OUs should be used to implement and limit security and roles among groups, while domains should be used to control Active Directory replication. Domain controllers Domain controllers are Windows Servers, which contain the Active Directory database and perform Active Directory related functions, including authentication and authorization. A domain controller is any Windows Server installed with the Domain Controller role.   Each domain controller stores a copy of the Active Directory database containing information about all objects within the same domain. In addition, each domain controller stores the schema for the entire forest, as well as all information about the forest. A domain controller will not store a copy of any schema or forest information from a different forest even if they are on the same network.   Specialized domain controller roles Specialized domain controller roles are used to perform specific functions that are not available on standard domain controllers. These master roles are assigned to the first domain controller created in each forest or domain. However, an administrator may manually reassign the roles.   Schema master Only one schema master exists per forest. It contains the master copy of the schema used by all other domain controllers. Having a master copy ensures that all objects are defined the same way.   Domain name master Only one domain name master exists per forest. The domain master ensures that all objects names are unique and, when necessary, cross-references objects stored in other directories.   Infrastructure master There is one infrastructure master per domain. The infrastructure master keeps the list of deleted objects and tracks references for objects on other domains.   Relative identifier master There is one relative identifier master per domain. It tracks the assignment and creation of unique Security Identifiers (SIDs) across the domain.   Primary Domain Controller Emulator There is only one Primary Domain Controller (PDC) Emulator per domain. It exists to provide backward compatibility from the older Windows NT-based domain systems. It responds to requests made to a PDC as an old PDC would have.   Data store Storage and retrieval of data on any domain controller is handled by the data store. The data store is composed of three layers. The bottom layer is the database itself. The middle layer is service components, the Directory System Agent (DSA), the database layer, and the Extensible Storage Engine (ESE). The top layer is the directory store services, LDAP (Lightweight Directory Access Protocol), the replication interface, the Messaging API (MAPI), and the Security Accounts Manager (SAM).    Domain Name System Active Directory contains location information on objects stored in the database, however Active Directory uses Domain Name System (DNS) to locate domain controllers.   Within the active directory, every domain has a DNS domain name and every joined computer has a DNS name within that same domain.   Objects Everything within Active Directory is stored as an object. The class could also be defined as the “type” of an object in the schema. The attributes are the components of the object – the attributes of an object are defined by its class.   Objects must be defined within the schema before data can be stored in the directory. Once defined, data is stored within the active directory as individual objects. Every object must be unique and represent a single thing, such as a user, computer, or a unique group of things (e.g. user group). The two primary types of objects are resources and security principals. Security principals are assigned Security Identifiers (SIDs), but resources are not.   Replication Active Directory uses multiple domain controllers for many reasons including load balancing and fault tolerance. For this to work, each domain controller must have a complete copy of its domain’s own Active Directory database. Ensuring that each controller has a current copy of the database occurs through replication.   Replication is limited by the domain. Domain controllers on different domains do not replicate between one another, even within the same forest. Every domain controller is equal. Although previous versions of Windows had Primary and Secondary domain controllers, there is no such thing in Active Directory. There is occasionally some confusion due to the continuation of the name ‘domain controller’ from the old trust-based system to Active Directory.   Replication works on a pull system, meaning that a domain controller requests or “pulls” the information from other domain controller rather than each domain controller sending or “pushing” data to others. By default, domain controllers request replication data every 15 seconds. Certain high-security events trigger an immediate replication event, such as an account lockout.   Only changes are replicated. To ensure fidelity across a multi-master system, each domain controller keeps track of changes and requests only the updates since the last replication. Changes are replicated throughout the domain using a store-and-forward mechanism such that any change is replicated when requested, even if the change did not originate on the domain controller answering the replication request.   This both prevents excess traffic and can be configured to ensure that each domain controller requests its replication data from the most desirable server. For example, a remote location with one fast connection and one slow connection to other sites with domain controllers can set a “cost” on each connection. In doing so, the replication request will be made across the faster connection.

 

 

What is Audio/Video Server ?

Overture provides media servers to make your music and videos easy to find. Media servers are a godsend when it comes to organizing and managing your movie and music collections. With a media server provided by Overture, you can browse your movie or music collection to find what you want and enjoy playback of your choice instantaneously. Say goodbye to DVD and CD clutter with a media server that can store and organize your movies and music electronically. Overture can recommend the right media server that will provide high-speed networking to deliver your favorite movies or music throughout your home. Instantly access and enjoy your movies or music CDs where it’s convenient for you, your family or your guests. Features of media servers include the following: Simplify the way you collect, manage, and enjoy your music and movies. Store and organize your collections electronically. Intuitive graphical interface allows for easy access and management of extensive video and music libraries. Simply type in the musician or actor you want to enjoy and the choices from your library will appear. Personalize your video viewing experience by creating your own favorite scenes, and even linking them together to create a video montage. For music, quickly select and play any album or track. You can also make customized mix albums.

 

Application Server ?

An application server consists of a server operating system (OS) and server hardware that work together to provide computing-intensive operations and services to the residing application. An application server executes and provides user and/or other app access when utilizing the installed application’s business/functional logic. Key required features of an application server include data redundancy, high availability, load balancing, user management, data/application security and a centralized management interface. Moreover, an application server may be connected by enterprise systems, networks or intranet and remotely accessed via the Internet.   Depending on the installed application, an application server may be classified in a variety of ways, including as a Web server, database application server, general purpose application server or enterprise application (EA) server.

 

Chat Server ?

Chat server is a standlone application that is made up the combination of two-application, server application (which runs on server side) and client application (which runs on client side). This application is using for chatting in LAN. To start chatting you must be connected with the server after that your message can broadcast to each and every client.    For making this application we are using some core java features like swing, collection, networking, I/O Streams and threading also. In this application we have one server and any number of clients (which are to be communicated with each other). For making a server we have to run the MyServer.java file at any system on the network that we want to make server and for client we have to run MyClient.java file on the system that we want to make client. For running whole client operation we can run the Login.java.

 

FTP Server ?

In the simplest of definitions, an FTP Server (which stands for File Transfer Protocol Server) is a software application which enables the transfer of files from one computer to another. FTP is a way to transfer files to any computer in the world that is connected to the internet. But what does all of this really mean? Why would someone want to use an FTP Server? FTP Explained FTP is a standard network protocol used for the transfer of files between a client and server on a computer network. FTP is a very well-established protocol, developed in the 1970s to allow two computers to transfer data over the internet. One computer acts as the server to store information and the other acts as the client to send or request files from the server. The FTP protocol typically uses port 21 as its main means of communication. An FTP server will listen for client connections on port 21. What Do FTP Servers Do? FTP servers, and the more secure SFTP Server software, perform 2 basic tasks: “Put” and “Get.” You can put files on the FTP Server or get files from the FTP Server. If security is not a concern, FTP Server software is an easy and inexpensive way to accomplish this. If you have remote employees who need to upload non-confidential information (such as timesheets, for example), or if you want to allow your customers to download white papers and documentation, an FTP Server works well for this purpose. If you are exchanging non-sensitive data with business partners, and the partner requires FTP or SFTP, you can quickly set up a server that will accept their data transfer. Some people even use FTP Servers for offsite backup so they can access their data should something physically happen to their files. Further, backup applications will often write to an FTP or SFTP Server; for example, if you’re backing up your Cisco Unified Call Manager (CUCM), the data must be backed up to an SFTP Server like Titan FTP Server. But Are FTP Servers Inherently Secure? Traditional FTP Servers do lack security- the only security feature that they really have is a login feature (username and password), which provides some degree of authentication and is a way to keep out unwanted users. However, secure FTP protocols do exist now to combat this issue. There are two main implementations of secure FTP: SFTP and FTP/S. These two secure file transfer protocols were designed to address the main weaknesses of FTP. For instance, both FTP/S and SFTP support encryption, which can keep a hacker from accessing data being transferred.

 

Fax Server ?

A fax server (or faxserver) is a system installed in a local area network (LAN) server that allows computer users who are attached to the LAN to send and receive fax messages. Fax messages can be stored as printable word processing, graphics, database, or spreadsheet files. Scanned documents can be sent as fax messages, allowing a computer and scanner to effectively emulate a dedicated fax machine.     A fax server is composed of a computer with a fax program, a fax modem (a modem capable of sending and receiving fax signals as well as conventional Internet data), a connection to the Internet or a telephone line, and connections to the LAN users.   There are several advantages to a fax server when compared with an ordinary fax machine. A single fax server can emulate multiple fax machines (one for each network user), thereby reducing overhead. Some functions can be automated. For example, a business fax server can automatically send invoices and purchase orders to customers and suppliers at specified times. Received faxes can be automatically stored as files on the server, and retrieved later by network users. In addition, a fax server can function without paper, reducing clutter and eliminating the need to continually check paper trays.   The term “fax server” is sometimes used to describe a program that enables a computer to send and receive fax messages.

 

DHCP Server ?

A DHCP Server is a network server that automatically provides and assigns IP addresses, default gateways and other network parameters to client devices. It relies on the standard protocol known as Dynamic Host Configuration Protocol or DHCP to respond to broadcast queries by clients.   A DHCP server automatically sends the required network parameters for clients to properly communicate on the network. Without it, the network administrator has to manually set up every client that joins the network, which can be cumbersome, especially in large networks. DHCP servers usually assign each client with a unique dynamic IP address, which changes when the client’s lease for that IP address has expired.   When to use a router/switch as your DHCP Server There are many enterprise companies who are still using DHCP for IPv4 on their routers/switches.  This is typically done by the network administrator who needs to get a DHCP capability up and running quickly but does not have access to a DHCP server. Most routers/switches have the ability to provide the following DHCP server support:       a DHCP client and obtain an interface IPv4 address from an upstream DHCP service a DHCP relay and forward UDP DHCP messages from clients on a LAN to and from a DHCP server a DHCP server whereby the router/switch services DHCP requests directly. However, there are limitations to using a router/switch as a DHCP server Running a DHCP server on a router/switch consumes resources on the network device.  These DHCP packets are handled in software (not hardware accelerated forwarding).  The resources required make this practice not suitable for a network with a large number (> 150) of DHCP clients. Does not support dynamic DNS.  The router/switch DHCP server cannot create an entry into DNS on behalf of the client based on the IPv4 address that was leased to the client. No ability to e asily manage the scope and see the current DHCP bindings and leases across multiple routers.  Administrator must log into the switch/router individually to get information about DHCP bindings. No high availability or redundancy of the DHCP bindings.  This could cause problems if the current DHCP server and default gateway fails. It is more difficult to configure DHCP options on router/switch platform. The DHCP service running on a router/switch is not integrated with IP address management (IPAM) for address tracking and scope utilization or security forensics.   The Benefits of a dedicated DHCP Server A better approach than trying to use DHCP on your router/switch is to use a centralized DHCP server. This is particularly true for network environments that require support of both DHCP for IPv4 and DHCP for IPv6 at the same time.  Virtually all DHCP server vendors support both protocols so you can use the same management interface for IPv4 and IPv6.  There are several benefits that make it advantageous for an enterprise to use DHCPv6.   Having a DHCPv6 server that is integrated into your IP Address Management (IPAM) system for IPv6 gives visibility to the IPv6-enabled client nodes. You also would want this same functionality for IPv4.  As IPv4 address space becomes increasingly constrained, you will want to keep track of your DHCP scopes and determine if your lease time is adequate with the plethora of BYOD systems joining your networked environment. DHCP servers provide logging and management interfaces that aid administrators manage their IP address scopes.  Your organization will want an accounting of what is on your network regardless of IP version being used. DHCP servers can provide redundancy and high availability.  If one DHCP server were to fail, the clients will preserve their current IP addresses and not cause an interruption for the end-nodes. Organizations will prefer a DHCPv6 server that has been tried and tested.  For example, The Infoblox DHCPv6 server has been certified as “IPv6 Ready” by the USGv6 certification laboratory. Organizations that are beginning to implement IPv6 should migrate DHCP for IPv4 scope off the routers/switches and put them on a robust DHCP server infrastructure. This change will also mean that your organization would want to have DHCP operate the same for both protocols.  Enterprise organizations will want to take advantage of the centralized dual-protocol DHCP server to provide IPv4 and IPv6 addresses to client devices.

 

File Server ?

As the name implies, a file server is a server that provides access to files. It acts as a central file storage location that can be accessed by multiple systems. File servers are commonly found in enterprise settings, such as company networks, but they are also used in schools, small organizations, and even home networks.   A file server may be a dedicated system, such as network attached storage (NAS) device, or it may simply be a computer that hosts shared files. Dedicated file servers are typically used for enterprise applications, since they provide faster data access and offer more storage capacity than non-dedicated systems. In home networks, personal computers are often used as file servers. However, personal NAS devices are also available for home users that require more storage capacity and faster performance than a non-dedicated file server would allow.     File servers can be configured in multiple ways. For example, in a home setting, a file server may be set to automatically allow access to all computers on the local network (LAN). In a business setting where security is important, a file server may require all client systems to log in before accessing the server. Others may only grant access to a specific list of machines, which can be defined by MAC address or IP address. Internet file servers, which provide access to files over the Internet, often require an FTP login before users can download files.   NOTE: When you connect to a file server on a local network, it usually appears as a hard disk on your computer. You can double-click the hard disk icon to view the contents and browse through directories on the server, just like local folders. If you want to copy a file from the server to your computer, simply drag the file to your desktop or another folder on your local disk. If the file server has write permissions enabled, you can also copy local files to the server by dragging them to a directory on the server. When you copy files to or from the file server, it may appear that they are simply being transferred from one local folder to another. However, the files are actually being transferred across the network.

 

DNS Server ?

A DNS server is a computer server that contains a database of public IP addresses and their associated hostnames, and in most cases serves to resolve, or translate, those names to IP addresses as requested. DNS servers run special software and communicate with each other using special protocols.   The Purpose of DNS Servers It’s easier to remember a domain or hostname like blog2india.com than it is to remember the site’s IP address numbers 151.101.129.121. When you want to navigate to the blog2india website, all you have to type in is the URL https://www.blog2india.com. Conversely, computers and network devices don’t work well with names when trying to locate each other on the internet. It’s far more efficient and precise to use an IP address.   Malware Attacks That Change DNS Server Settings It’s always important to be running an antivirus program. One reason is that malware can attack your computer in a way that changes the DNS server settings, which is definitely something you don’t want to happen.   For example, if your computer uses Google’s DNS servers (8.8.8.8 and 8.8.4.4) and you navigate to your bank’s website, you naturally expect that when you enter its familiar URL, you’ll be sent to the bank’s website.   However, if malware changes your DNS server settings, which can happen without your knowledge after an attack on your system, your system is no longer contacting Google’s DNS servers but instead a hacker’s server that poses as your bank’s website. This fake bank site might look exactly like the real one, but rather than logging you into your bank account, it harvests your username and password you just typed in, giving the hackers the essential information they need to get into your bank account.   Malware attacks that hijack your DNS server settings may also redirect traffic away from popular websites to ones that are full of advertisements or a fake site that is designed to scare you into believing your computer has been infected with a virus, and that you must buy their advertised software program to remove it.     Protecting Yourself From DNS Attacks There are two things you should do to avoid becoming a victim of a DNS settings attack. The first is to install antivirus software so that malicious programs are caught before they can do any damage.   The second is to pay close attention to the appearance of important websites you visit regularly. If you visit one and the site looks off in some way—maybe the images are all different or the site’s colors have changed, or menus don’t look right, or you find misspellings (hackers can be dreadful spellers)—or you get an “invalid certificate” message in your browser, it might be a sign that you’re on a faked website.   How DNS Redirection Can Be Positively Used This ability to redirect traffic can be used for positive purposes. For example, OpenDNS can redirect traffic to adult websites, gambling websites, social media websites, or other sites network administrators or organizations don’t want their users visiting. Instead, they may be sent to a page with a “Blocked” message.   Primary and Secondary DNS Servers In most cases, a primary and a secondary DNS server are configured on your router and/or computer when you are connected to your internet service provider (ISP). There are two DNS servers in case one of them happens to fail, in which case the second is used to resolve hostnames you enter.   DNS Root Servers There are 13 important DNS root servers on the internet that store a complete database of domain names and their associated public IP addresses. These top-tier DNS servers are named A through M for the first 13 letters of the alphabet. Ten of these servers are in the US, one in London, one in Stockholm, and one in Japan.   The Internet Assigned Numbers Authority (IANA) keeps this list of DNS root servers if you’re interested.

 

Mail Server ?

A mail server (or email server) is a computer system that sends and receives email. In many cases, web servers and mail servers are combined in a single machine. However, large ISPs and public email services (such as Gmail and Hotmail) may use dedicated hardware for sending and receiving email.   In order for a computer system to function as a mail server, it must include mail server software. This software allows the system administrator to create and manage email accounts for any domains hosted on the server. For example, if the server hosts the domain name “techterms.com,” it can provide email accounts ending in “@techterms.com.”   Mail servers send and receive email using standard email protocols. For example, the SMTP protocol sends messages and handles outgoing mail requests. The IMAP and POP3 protocols receive messages and are used to process incoming mail. When you log on to a mail server using a webmail interface or email client, these protocols handle all the connections behind the scenes.   Mail server software is available for multiple platforms. The most popular mail server for Windows is Microsoft Exchange Server, an enterprise product used by large businesses. However, many other options exist, including Ipswitch IMail Server, IceWarp Mail Server, MailEnable, and hMailServer. Popular Linux options include Exim for sending mail and Dovecot and Courier for receiving mail.

 

News Server ?

A news server can be defined as a computer which is primarily or solely used for handling Usenet articles.   A reader server – with news client assistance – provides an valuable interface to read and post articles.   A transit server interacts with other servers by exchanging articles. Most servers can provide both functions.   In the past, servers normally employed the UUCP protocol, which was designed for intermittent dial-up connections. News servers normally connect with the multiple peers, keeping in mind that in mind that neither of the information is lost over the channel and uniformly distributing the loads. Leaf nodes ie. smaller sites, are connected to one of the major server.   Modern transit servers usually use NNTP to exchange news continually over the Internet and hence are more reliable.

 

Proxy Server ?

A proxy server is a dedicated computer or a software system running on a computer that acts as an intermediary between an endpoint device, such as a computer, and another server from which a user or client is requesting a service. The proxy server may exist in the same machine as a firewall server or it may be on a separate server, which forwards requests through the firewall.   An advantage of a proxy server is that its cache can serve all users. If one or more Internet sites are frequently requested, these are likely to be in the proxy’s cache, which will improve user response time. A proxy can also log its interactions, which can be helpful for troubleshooting.    How proxy servers work When a proxy server receives a request for an Internet resource (such as a Web page), it looks in its local cache of previously pages. If it finds the page, it returns it to the user without needing to forward the request to the Internet. If the page is not in the cache, the proxy server, acting as a client on behalf of the user, uses one of its own IP addresses to request the page from the server out on the Internet. When the page is returned, the proxy server relates it to the original request and forwards it on to the user.   Proxy servers are used for both legal and illegal purposes. In the enterprise, a proxy server is used to facilitate security, administrative control or caching services, among other purposes. In a personal computing context, proxy servers are used to enable user privacy and anonymous surfing. Proxy servers can also be used for the opposite purpose: To monitor traffic and undermine user privacy.   To the user, the proxy server is invisible; all Internet requests and returned responses appear to be directly with the addressed Internet server. (The proxy is not actually invisible; its IP address has to be specified as a configuration option to the browser or other protocol program.)

 

Telnet Server ?

Telnet protocol is intended to provide a fairly general, bi-directional, eight-bit byte oriented communications facility. The main goal is to allow a standard method of interfacing terminal devices to each other.   MikroTik RouterOS implements industry standard Telnet server. It uses port 23, which must not be disabled on the router in order to use the feature.   You can enable/disable this service or allow the use of the service to certain IP addresses. See the System Services manual for the detailed instructions

 

Virtual Server ?

A virtual server is a server that shares hardware and software resources with other operating systems (OS), versus dedicated servers. Because they are cost-effective and provide faster resource control, virtual servers are popular in Web hosting environments.   Ideally, a virtual server mimics dedicated server functionalities. Rather than implement multiple dedicated servers, several virtual servers may be implemented on one server.   Each virtual server is designated a separate OS, software and independent reboot provisioning. In a virtual server environment for Web hosting, website administrators or Internet service providers (ISP) may have different domain names, IP addresses, email administration, file directories, logs and analytics. Additionally, security systems and passwords are maintained as if they were in a dedicated server environment. To reduce Web hosting costs, server software installation provisioning is often available.   An overflow of virtual servers in a physical machine may lead to resource hogging, and if a virtual server uses more resources than another, performance issues usually result.

 

Web Server

It provides static content to a web browser by loading a file from a disk and transferring it across the network to the user’s web browser. This exchange is intermediated by the browser and the server, communicating using HTTP.   Other types of servers include Open source servers, Gopher server (like a plain document, similar to WWW and the hypertext being absent), and Name server (applies name-service protocol).   The various servers can be categorized according to their applications. Servers along with managing network resources are also dedicated, i.e., they perform no other task other than their server tasks.

IRC Server

Internet Relay Chat (IRC) is a system for chatting that involves a set of rules and conventions and client/server software. On the Web, certain sites such as Talk City or IRC networks such as the Undernet provide servers and help you download an IRC client to your PC. Talk City also offers an IRC client applet that it downloads for you as part of their home page so that you can start chatting right away.   You can start a chat group (called a channel) or join an existing one. There is a protocol for discovering existing chat groups and their members. Depending on the type of network, nicknames can be reserved (registered) or just used during the session. Some channels encourage you to register a nickname that you always use and even offer space for a personal profile, picture, and personal home page link.   Popular ongoing IRC channels are #hottub and #riskybus. A number of channels are set up and conducted in foreign languages. The most common IRC networks are IRCnet (mostly European), EFnet (mostly North American), Undernet, and Dalnet. Popular IRC clients include mIRC for Windows, IRCle for Mac OS, and irc2 (the original client) for UNIX-base operating systems.   The IRC protocol uses Transmission Control Protocol (you can IRC via a Telnet client), usually on port 6667.