Data Flow – DNS Resolution with AD and F5 BIG-IP DNS

1. Local Cache Check: You attempt to access a website (say, ``) on your Windows AD-managed laptop. Your operating system first checks its local DNS cache to see if it already knows the IP address for ``. If it does, it uses this IP and the process stops here. If not, it moves to the next step.

2. Windows AD DNS Server Query: The laptop sends a DNS query to the DNS server configured on its network interface, usually obtained via DHCP. In a Windows Active Directory (AD) environment, this is typically a domain controller (DC) acting as a DNS server.

3. Windows AD DNS Server Resolution: The AD DNS Server checks its local cache. If it doesn’t find the record in its cache, it then checks its own DNS records in its Forward Lookup Zones. In this case, the AD DNS Server would find a CNAME record for `` pointing to a hostname managed by F5 BIG-IP DNS, such as ``.

4. DNS Delegation to F5 BIG-IP DNS: Because you’ve configured a delegation for the `` DNS zone, the AD DNS Server recognizes that it is not responsible for directly resolving ``. Instead, it forwards the request to the F5 BIG-IP DNS, whose address is specified in the NS record for the `` DNS zone.

5. F5 BIG-IP DNS Resolution: The F5 BIG-IP DNS system receives the DNS request and resolves it. F5 BIG-IP DNS is a global server load balancing (GSLB) solution, and it has its own method of resolving DNS queries. It could return an IP address based on factors such as geolocation, server load, etc.

6. Response Propagation: The F5 BIG-IP DNS sends the resolved IP address back to the originating AD DNS server, which in turn sends it back to your laptop.

7. Connection Initiation: The Windows laptop then uses the received IP address to connect to the desired web resource, which could be a web server or any other service reachable via IP.

This is a detailed sequence, but please note that the actual process may vary based on your specific infrastructure and configuration.