DNS , AD , DHCP - Chaithanyaa7/VMware GitHub Wiki
AD ( Active Directory )
Active Directory (AD) is a directory service developed by Microsoft for Windows domain networks. It manages and organizes resources like users, computers, and devices within a network. AD provides centralized authentication and authorization, allowing administrators to control access to network resources, enforce security policies, and manage user accounts.
DNS
DNS (Domain Name System) is a system that translates human-readable domain names (like www.example.com) into IP addresses (like 192.0.2.1) that computers use to identify each other on the network. It acts like a phonebook for the internet, allowing users to access websites and services with easy-to-remember names.
Common DNS Record Types:
A Record (Address Record): Maps a domain to an IPv4 address. AAAA Record: Maps a domain to an IPv6 address.
CNAME Record (Canonical Name Record): Redirects one domain name to another (aliasing).
MX Record (Mail Exchange Record): Directs email to mail servers for a domain.
NS Record (Name Server Record): Specifies the authoritative name servers for a domain.
PTR Record (Pointer Record): Used for reverse DNS lookups, mapping an IP address to a domain name.
TXT Record: Stores text information, often for verification and security purposes (like SPF or DKIM for email).
SRV Record (Service Record): Specifies the location of services like SIP or LDAP.
SOA Record (Start of Authority Record): Contains administrative information about the zone, such as the primary name server and email of the domain administrator.
DNS resolves queries from users and helps route internet traffic efficiently.
DHCP
DHCP (Dynamic Host Configuration Protocol) is a network management protocol used to automatically assign IP addresses and other network configuration details (like subnet mask, default gateway, and DNS servers) to devices on a network. This helps devices communicate efficiently without requiring manual configuration.
DORA Process in DHCP: The DORA process outlines the four steps used by DHCP to assign an IP address to a client:
Discovery: The client broadcasts a DHCP Discover message to find available DHCP servers on the network. Offer: DHCP servers respond with a DHCP Offer message, offering an available IP address and configuration details. Request: The client selects one offer and sends a DHCP Request message back to the chosen server to confirm it wants to use the provided IP address. Acknowledgement: The DHCP server responds with a DHCP Acknowledgment (ACK) message, confirming the lease and providing the client with network configuration details. This DORA process ensures the client receives a valid IP address and network settings dynamically, reducing the need for manual configuration and minimizing IP conflicts.
APIPA (Automatic Private IP Addressing) is a feature in Windows that assigns an IP address automatically to a device when the DHCP server is unavailable or no DHCP server is present. This allows devices to communicate within the same local network (subnet) even when a DHCP server cannot be reached.
APIPA IP Range: APIPA assigns IP addresses from the range 169.254.0.1 to 169.254.255.254 with a subnet mask of 255.255.0.0. Devices with APIPA IP addresses can communicate with each other on the same network segment but cannot access external networks like the internet. APIPA is mainly used for small networks or as a fallback mechanism when DHCP fails.