DOMAIN NAMING SYSTEM(DNS)

What is DNS:-

• Domain Name Service/Domain Name System

• Provides resolution of name to IP addressing and resolution of IP addresses to names

• Define a hierarchical namespace where level of the namespace is separated by a “.”

 Computer running DNS Service can be:-

DNS Namespace:-

How DNS Queries Work:-

Authoritative & Non-authoritative DNS Server:-

• Return the request IP address

• Return an authoritative “NO”

An Non-authoritative DNS Server will either:-

• Check its cache

• Use forwarders

• Use root hints

Fully Qualified Domain Name (FQDN):-

• Identifies a host’s name within the DNS namespace hierarchy

• Host name + DNS domain name = FQDN

• Example:

                      - Host name: sys1 & Domain name: WindowsAdmin.com
                      - Then FQDN = sys1.WindowsAdmin.com

Look up Types:-

ZONE:-

• Forward Lookup Zone

                 - Used for Resolving Host Name to IP-Address
                 - It maintains Host to IP Address Mapping Information

• Reverse Lookup Zone

                - Used for Resolving IP-Address to Host Name
                - It maintains IP Address to host Mapping Information

Types of Records:-
1. SOA Record
            - The first in any zone file
2. N S Record
            - Identifies the DNS server for each zone
3. Host Record
            - Resolves an alias name to a host name
4. Alias Record
            - Resolves an alias name to a host name
5. Pointer Record
            - Resolves an IP address to a host
6. MX Records
            - Used by the mail server
7.SRV Records (Service Records)
            - Resolves names of server providing services

Zone Types:-
1. Standard Primary
            - It is the Master Copy of all zone information. It is Read/Write copy
2. Standard Secondary
            - It is Backup to Primary zone. It
3. Stub Zone
            - It contains only NS, SOA & possibly Glue (A) Records with are used to locate name servers
4. Active Directory Integrated
            - It stores the information of Zone in ACTIVE DIRECTORY DATABASE

What are Service Records:-

• SRV records allow DNS client to locate TCP/IP-based Services.

• SRV record are used when:

            - A domain controller needs to replicate
            - A client searches Active Directory
            - A user attempts to change her password
            - An administrator modifies Active Directory