DNS

The Domain Name System (DNS) is a hierarchical distributed database that contains mappings of DNS domain names to various types of data, such as IP addresses. DNS allows you to use friendly names to easily locate computers and other resources on a TCP/IP network.

DNS is a key infrastructure component frequently used by various Parallels RAS components. While standard file-based storage, such as the hosts file, will provide proper DNS resolution in Proof of Concept (POC) environments, Parallels recommends implementing Active Directory integrated DNS in enterprise deployments.

Parallels recommends the use of the DNS zone integrated with Active Directory so that organizations can have the benefit of using secure dynamic updates, as well as the ability to use Access Control List (ACL) editing features to control which machines can update the DNS system.

Dynamic updates are a key feature of DNS, which allows domain computers to register their name and IP addresses with the DNS server automatically when they come online or change IP addresses through the DHCP server. The DNS Server service allows dynamic update to be enabled or disabled on a per-zone basis on each server that is configured to load either a standard primary or directory-integrated zone. By default, the DNS Client service dynamically updates host (A) resource records in DNS when the service is configured for TCP/IP. This form of update eliminates the need for manual entries of names and IP addresses into the DNS database.

There is a security concern when automatic update from a client to the DNS database could take place and thus create the possibly for a malicious entry. Therefore, secure dynamic updates will verify that the computer that is requesting the update to the DNS server also has an entry in the Active Directory database. This means that only computers that have joined the Active Directory domain can dynamically update the DNS database.

More information on how DNS works can be found at https://technet.microsoft.com/library/cc772774.aspx.

Reverse Lookup

In most Domain Name System (DNS) lookups, clients typically perform a forward lookup, which is a search based on the DNS name of another computer as it is stored in a host (A) resource record. This type of query expects an IP address as the resource data for the answered response.

DNS also provides a reverse lookup process in which clients use a known IP address and look up a computer name based on its address.