Workflow

The transparent DNS proxy is implemented by changing the destination IP address of DNS requests.

Figure 57: Transparent DNS proxy workflow

Table 13: Workflow description

Step

Source IP address

Destination IP address

1. An intranet user on the client host sends a DNS request to the LB device.

Host IP address

IP address of DNS server A

2. The LB device selects a DNS server to forward the DNS request according to the scheduling algorithm.

N/A

N/A

3. The LB device changes the destination IP address of the DNS request as the IP address of the selected DNS server.

  • Host IP address

IP address of the selected DNS server

4. The DNS server processes the DNS request and replies with a DNS response.

IP address of the selected DNS server

Host IP address

5. The LB device changes the source IP address of the DNS response as the destination IP address of the DNS request.

IP address of DNS server A

Host IP address

6. The intranet user accesses the external server according to the resolved IP address in the DNS response.

Host IP address

IP address of the external server

7. The external server responds to the intranet user.

IP address of the external server

Host IP address