A security researcher discovered that Applebot had been using a proxy that leaked Apple’s internal IP addresses. It took Apple just a little over 9 months to fix this leak, for no obvious reason. A proxy server is a middle agent between a device attempting to connect to a destination on the internet, and the destination itself. Applebot is the web crawler that sweeps the web to find content for its users and products like Siri and Spotlight Suggestions use Applebot, according to Apple’s knowledgebase.
Source: https://www.bleepingcomputer.com/news/security/apple-search-bot-leaked-internal-ips-via-proxy-configuration/