Domain Name Server

The Domain Name System (DNS) is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a  private network. It associates various information with domain names assigned to each of the participating entities. A Domain Name Service resolves queries for these names into IP Addresses for the purpose of locating computer services and devices worldwide. By providing a worldwide, distributed KEYWORD-based redirection service, the Domain Name System is an essential component of the functionality of the  Internet.

An often-used analogy to explain the Domain Name System is that it serves as the phone book for the Internet by translating human-friendly computer  host name into IP Addresses. For example, the domain name www.example.com translates to the addresses 192.0.43.10 (V4) and 2620:0:2d0:200::10 (V6). Unlike a phone book, however, DNS can be quickly updated and these updates distributed, allowing a service's location on the network to change without affecting the end users, who continue to use the same hostname. Users take advantage of this when they recite meaningful   (URLs) and  E-mail address without having to know how the computer actually locates the services.

The Domain Name System distributes the responsibility of assigning domain names and mapping those names to IP addresses by designating  name server for each domain. Authoritative name servers are assigned to be responsible for their particular domains, and in turn can assign other authoritative name servers for their sub-domains. This mechanism has made the DNS distributed and fault tolerant and has helped avoid the need for a single central register to be continually consulted and updated. Additionally, the responsibility for maintaining and updating the master record for the domains is spread among many DNR, who compete for the end-user's, domain-owner's, business. Domains can be moved from registrar to registrar at any time.


In this video you will learn basic concept of DNS 

DHCP What is DHCP? The Dynamic Host Configuration Protocol (DHCP) is a protocol that is used to configure network devices so that they can communicate on an IP network. A DHCP client uses the DHCP protocol to acquire configuration information, such as an IP address, a default route and one or more DNS server addresses from a DHCP server. The DHCP client then uses this information to configure its host. Once the configuration process is complete, the host is able to communicate on the internet.The DHCP server maintains a database of available IP addresses and configuration information. When it receives a request from a client, the DHCP server determines the network to which the DHCP client is connected, and then allocates an IP address or prefix that is appropriate for the client, and sends configuration information appropriate for that client. Because the DHCP protocol must work correctly even before DHCP clients have been configured, the DHCP server and DHCP client must be connected to the same network link. In larger networks, this is not practical. On such networks, each network link contains one or more DHCP relay agents. These DHCP relay agents receive messages from DHCP clients and forward them to DHCP servers. DHCP servers send responses back to the relay agent, and the relay agent then sends these responses to the DHCP client on the local network link. DHCP servers typically grant IP addresses to clients only for a limited interval. DHCP clients are responsible for renewing their IP address before that interval has expired, and must stop using the address once the interval has expired, if they have not been able to renew it. DHCP is used for IPv4 and IPv6. While both versions serve much the same purpose, the details of the protocol for IPv4 and IPv6 are sufficiently different that they may be considered separate protocols. Hosts that do not use DHCP for address configuration may still use it to obtain other configuration information. Alternatively, IPv6 hosts may use stateless address autoconfiguration. IPv4 hosts may use link-local addressing to achieve limited local connectivity.

Backup Windows Server 2008 Active Directory

Backing up Active Directory is essential to maintain an Active Directory database. A system state backup is particularly important for disaster recovery purpose in case of a accidental corruption or deletion of Active Directory objects. Since Windows Server 2008, you won’t find the well-known ntbackup.exe, the native backup tool in previous Windows versions. Instead, you use Windows Server Backup, the new native backup solution, which is available as an installation option in all versions of Server 2008.

Tips: If you forgot domain administrator password in Active Directory and can’t log on the domain controller, you can reset/unlock any domain user account passwords easily with Reset Windows Password utility.

WEB Server

Web server can refer to either the hardware (the computer) or the software (the computer application) that helps to deliver Web content that can be accessed through the Internet. 

The most common use of web servers is to host websites, but there are other uses such as gaming , data storage or running enterprise applications.

The primary function of a web server is to deliver web pages on the request to clients using the Hypertext Transfer Protocol (HTTP). This means delivery of HTML documents and any additional content that may be included by a document, such as images, style sheets and scripts.

A user agent, commonly a web browser or web crawler, initiates communication by making a request for a specific resource using HTTP and the server responds with the content of that resource or an error message if unable to do so. The resource is typically a real file on the server's secondary storage, but this is not necessarily the case and depends on how the web server is implemented.

While the primary function is to serve content, a full implementation of HTTP also includes ways of receiving content from clients. This feature is used for submitting web forms, including uploading of files.

Many generic web servers also support server-side scripting using Active Server Pages (ASP), PHP, or other scripting languages. This means that the  behavior of the web server can be scripted in separate files, while the actual server software remains unchanged. Usually, this function is used to create HTML documents dynamically ("on-the-fly") as opposed to returning static documents. The former is primarily used for retrieving and/or modifying information from databases. The latter is typically much faster and more easily cached.

Web servers are not always used for serving the World Wide Web. They can also be found embedded in devices such as printers, routers, webcams and serving only a local network. The web server may then be used as a part of a system for monitoring and/or administering the device in question. This usually means that no additional software has to be installed on the client computer, since only a web browser is required (which now is included with most operating systems).

Windows server 2008

Windows Server powers many of the worlds' largest data centers  enables small businesses around the world, and delivers value to organizations of all sizes in between. Windows Server 2012 redefines the server category, delivering hundreds of new features and enhancements spanning virtualization, networking, storage, user experience, cloud computing, automation, and more. Simply put, Windows Server 2012 helps you transform your IT operations to reduce costs and deliver a whole new level of business value.

If we talk about active directory we will realize that active directory is the main object of windows server 2008.
However. active directory cannot work without domain controller in this situation both active directory and domain 
controller have the same important.

Active Diroctory Active Directory (AD) is a directory service  created by Microsoft  for Windows domain windows server   operating systems. Active Directory provides a central location for network administration and security. Server computers that run Active Directory are called domain controller. An AD domain controller   authenticates and authorizes all users and computers in a Windows domain type network assigning and enforcing security policies for all computers and installing or updating software. For example, when a user logs into a computer that is part of a Windows domain, Active Directory checks the submitted password and determines whether the user is a system administrator or normal user.

Domain Controllr

A domain controller is a server that is running a version of the Windows Server® operating system and has Active Directory® Domain Services installed.

What is the key benefit of Microsoft Domain Security?

In a word, single sign-on, or SSO for short. To many, this is the Holy Grail of MS Windows NT and beyond networking. SSO allows users in a well-designed network to log onto any workstation that is a member of the domain that contains their user account (or in a domain that has an appropriate trust relationship with the domain they are visiting) and they will be able to log onto the network and access resources (shares, files, and printers) as if they are sitting at their home (personal) workstation. This is a feature of the domain security protocols.

The benefits of domain security are available to those sites that deploy a Samba PDC. A domain provides a unique network security identifier (SID). Domain user and group security identifiers are comprised of the network SID plus a relative identifier (RID) that is unique to the account. User and group SIDs (the network SID plus the RID) can be used to create access control lists (ACLs) attached to network resources to provide organizational access control. UNIX systems recognize only local security identifiers.

A SID represents a security context. For example, every Windows machine has local accounts within the security context of the local machine which has a unique SID. Every domain (NT4, ADS, Samba) contains accounts that exist within the domain security context which is defined by the domain SID.