Adding details to Dns lookup section #2477
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Enhancements Made:
Detailed Browser Cache Check:
Added information on how the browser first checks its DNS cache before proceeding with further resolution steps. Instructions for viewing the DNS cache in Chrome (chrome://net-internals/#dns) were included.
Clarification on Lookup Function:
Explained the role of the gethostbyname library function in performing the DNS lookup when the domain is not found in the cache.
Local Hosts File Resolution:
Included details about the browser checking the local hosts file for hostname resolution before querying the DNS server.
DNS Server Request Process:
Described the process of making a request to the configured DNS server when the hostname is not found in the cache or hosts file.
Address Resolution Protocol (ARP) Explanation:
Provided a detailed explanation of how ARP is used to resolve the IP address of the DNS server when it is located on the same subnet. This includes the process of sending ARP requests and receiving MAC addresses.
Cross-Subnet DNS Resolution:
Explained how ARP is utilized for the default gateway when the DNS server is on a different subnet, ensuring clarity on how network communication is established.
In-Depth DNS Query Process:
Enhanced the description of the DNS query process, detailing how the DNS server checks its cache, performs recursive queries, and communicates with root and authoritative DNS servers to resolve the domain name.
Final Steps Summary:
Summarized the final steps that occur after the IP address is obtained, leading to the initiation of a TCP connection for further communication.