What is 8.8.4.4?
8.8.4.4 is the secondary IP address of Google Public DNS. It provides the same recursive DNS resolution service as 8.8.8.8 and is used as a fallback when the primary resolver is unavailable. Both addresses are operated by Google LLC through its anycast infrastructure.
Privacy note
Seeing 8.8.4.4 in a DNS leak test alongside 8.8.8.8 is typical when Google DNS is the system resolver. If you're connected to a VPN and see this address, your VPN is not enforcing its own DNS server.