Network address translation (NAT) in DNS refers to the process of translating IP addresses between different networks. It allows multiple devices within a local network to share a single public IP address. When a device from the local network communicates with external servers or devices over the internet, NAT dynamically assigns a unique port number to distinguish each connection. This enables efficient use of limited public IP addresses and helps manage the flow of incoming and outgoing data.
The network address translator (NAT) is a device or software that implements NAT. It acts as an intermediary between devices on a local network with private IP addresses and the external network with public IP addresses. The NAT device maintains a mapping table that keeps track of which internal IP addresses and ports correspond to which external IP addresses and ports. This allows it to correctly route incoming and outgoing traffic while preserving the integrity and security of the internal network.
Address translation in DNS refers to translating domain names (like www.example.com) into IP addresses (like 192.0.2.1) that computers use to identify each other on a network. DNS servers perform this translation, mapping human-readable domain names to numerical IP addresses that computers and network devices can understand and use to communicate over the internet.
NAT works step by step by intercepting and altering network packets as they pass through the NAT device:
- Packet Capture: The NAT device captures outgoing packets from devices within the local network.
- Address Translation: It modifies the source IP address and port number of each outgoing packet, replacing the private IP address and port with its own public IP address and a unique port number.
- Routing: The NAT device then forwards the packet to the destination server on the internet using the translated address and port.
- Response Translation: When the server sends back a response, the NAT device translates the destination IP address and port number back to the original private IP address and port of the requesting device.
- Packet Forwarding: Finally, the NAT device forwards the translated packet to the appropriate device within the local network based on the information stored in its mapping table.
This process allows devices with private IP addresses to communicate with servers and devices on the internet using a shared public IP address, effectively extending the usability of IPv4 addresses and enhancing network security by masking internal network structures.