Quick Study Revision Points: DNS (Domain Name System) and DHCP (Dynamic Host Configuration Protocol)
Table of contents
DNS (Domain Name System):
Definition: DNS is a distributed naming system that translates human-readable domain names into IP addresses, allowing users to access websites and services using domain names.
DNS Hierarchy:
Root DNS Servers: Top-level servers that store information about the root of the DNS hierarchy.
Top-Level Domain (TLD) Servers: Servers responsible for specific TLDs like .com, .org, or country-specific TLDs.
Authoritative DNS Servers: Servers that store DNS records for specific domain names.
Recursive DNS Servers: Intermediate servers that perform recursive queries to resolve domain names by traversing the DNS hierarchy.
DNS Resolution Process:
Recursive Query: The client sends a DNS query to a recursive DNS server.
Iterative Query: The recursive DNS server contacts other DNS servers to resolve the query.
Response: The recursive DNS server provides the resolved IP address back to the client.
DNS Records:
A (Address) Record: Maps a domain name to an IPv4 address.
AAAA (IPv6 Address) Record: Maps a domain name to an IPv6 address.
CNAME (Canonical Name) Record: Creates an alias for a domain name.
MX (Mail Exchanger) Record: Specifies the mail server responsible for accepting emails for a domain.
NS (Name Server) Record: Indicates the authoritative DNS servers for a domain.
DHCP (Dynamic Host Configuration Protocol):
Definition: DHCP is a network protocol that dynamically assigns IP addresses and network configuration parameters to devices on a network.
DHCP Lease Process:
DHCP Discover: The client broadcasts a DHCP Discover message to find available DHCP servers.
DHCP Offer: The DHCP server responds with a DHCP Offer message, offering an IP address lease to the client.
DHCP Request: The client sends a DHCP Request message, indicating acceptance of the offered IP address.
DHCP Acknowledgment: The DHCP server sends a DHCP Ack message, confirming the lease and providing network configuration information.
DHCP Options:
IP Address Lease: The duration for which the IP address is assigned to the client.
Subnet Mask: Defines the network subnet for the client.
Default Gateway: Specifies the default gateway or router for the client to access other networks.
DNS Servers: Provides the IP addresses of DNS servers for name resolution.
Domain Name: Specifies the domain name associated with the IP address.
DHCP Relay: Used to forward DHCP messages between different network segments, enabling centralized DHCP server management.