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.