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28 Data Center & Hybrid Cloud Security For Dummies, Palo Alto Networks Special Edition These materials are © 2020 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited. At a high level, a DNS lookup generally involves the following steps (see Figure 2-2): 1. A user initiates a query by typing a Uniform Resource Locator (URL) into a web browser. The query is sent to a DNS resolver, which is a server usually provided by an IP provider. The DNS resolver matches the URL to its corresponding IP address. 2. The resolver queries one of the DNS root servers. Root servers are distributed around the world and hold the locations of all top-level domains (TLDs) such as .com, .edu, and .net. 3. The root server sends a response to the resolver. 4. The resolver can now query the appropriate TLD server. 5. The TLD server doesn't hold the IP address for specific domains, but it knows the locations of the authoritative name servers for specific domains. 6. The DNS resolver queries one of the authoritative name servers. 7. The authoritative name server knows the IP address and responds with an address record. 8. The DNS resolver sends the IP address of the web server back to the user's device. 9. The website loads in the browser. FIGURE 2-2: The DNS resolution process.