CCNA Discovery 2, Chapter 7

7.3.1: As mentioned, a domain name such as cisco.com is easier to remember than an IP address. Each network host contains a HOSTS file that matches names to IP addresses. This HOSTS file is scanned first by the host to resolve a request for a domain. However, this HOSTS file contains a very limited list of names and IP addresses, so a DNS server performs the bulk of domain resolution on a network.

7.3.2: DNS operates using a hierarchical structure in which many servers across the Internet maintain a distributed database of hostname-to-IP mappings. DNS servers maintain hostname-to-IP mappings for their zone. If a DNS server receives a request for DNS resolution of a domain outside its zone, the DNS server forwards the ...

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