Domain name system

As explained in ASP.NET Core in Action, 3e

DNS is the hierarchical naming system that resolves hostnames to IP addresses and other network records.

The Domain Name System (DNS) maps a website hostname to an IP address. When someone enters a URL, the hostname helps locate the server that receives the browser’s HTTP request. section 1.4.1

A typical request uses DNS as part of this sequence:

• The user navigates to a URL containing a hostname and path. section 1.4.1
• DNS maps the hostname to the server’s IP address. section 1.4.1
• The client connects to that IP address and sends an HTTP request. section 1.4.1

DNS also matters when an application calls another service with HttpClient. HttpClient performs a DNS lookup before establishing a connection. If the DNS record changes, a long-lived client may continue using the originally resolved server. section 33.1

Figure 1.2 Requesting a web page. The user starts by requesting a web page, which causes an HTTP request to be sent to the server. The server interprets the request, generates the necessary HTML, and sends it back in an HTTP response. Then the browser can display the web page.

Follow the request from browser navigation through HTTP communication and the server response. section 1.4.1

Figure 33.3 HttpClient does a DNS lookup before establishing a connection to determine the IP address associated with a hostname. If the DNS record for a hostname changes, a singleton HttpClient will not detect it and will continue sending requests to the original server it connected to.

Inspect how HttpClient resolves a hostname before connecting and why DNS changes can affect singleton clients. section 33.1

How ASP.NET Core in Action, 3e covers it

How deep it goes

Defines hostname-to-IP mapping and lookup timing, but stops short of DNS record types or resolver internals.

Examples

Uses microsoft.com, www.google.co.uk, facebook.com, and HttpClient connections as concrete hostname examples.

What it assumes

Assumes basic browser and HTTP request flow while defining hostname and IP address from zero.

What you can do after

Evaluate how hostname resolution precedes HTTP connections and why changing DNS can affect long-lived HttpClient instances.

How it connects

Connects hostnames, IP addresses, URLs, HTTP requests, and HttpClient.

liveBookmanning.com

Read ASP.NET Core in Action, 3e on liveBook Get the book at manning.com

Also explained in

• 

  liveBookmanning.com
  Acing the CCNA Exam: Volume 2 Advanced Networking and SecurityThe Domain Name System is a distributed naming system that translates domain names into network addresses and related resource records.
• 

  liveBookmanning.com
  Acing the Certified Kubernetes Administrator Exam, Second EditionThe Domain Name System, a hierarchical naming system that resolves domain or resource names to network addresses.
• 

  liveBookmanning.com
  Build Python Web Apps with StreamlitDNS is the naming system that maps human-readable domain names and subdomains to network resources.
• 

  liveBookmanning.com
  Rust in Action: Systems programming concepts and techniquesThe Domain Name System is a distributed naming system that maps domain names to network resource records such as IP addresses.
• 

  liveBookmanning.com
  Learn Docker in a Month of Lunches, Second EditionDNS is the Domain Name System, a distributed naming system that resolves domain names to network addresses.
• 

  liveBookmanning.com
  Grokking Web Application SecurityThe Domain Name System (DNS) is the hierarchical naming system that maps domain names to network addresses and other DNS records.

Compare how 7 books explain domain name system →

Related concepts

• UDPuses · UDP (User Datagram Protocol) is a connectionless transport-layer protocol that sends datagrams without guaranteeing delivery, ordering, or duplicate suppression.
• TCPuses · TCP is a connection-oriented transport-layer protocol that provides reliable, ordered delivery of byte streams between network endpoints.
• IP addressproduces · An IP address is a numerical address used by the Internet Protocol to identify a network interface and support packet delivery across networks.
• nslookupused by · nslookup is a command-line utility that queries Domain Name System servers and displays domain names, addresses, and other resource records.
• service discoveryused by · Service discovery is the process of identifying available services and obtaining the names, locations, or connection information needed to access them.
• CoreDNSused by · CoreDNS is an extensible, plugin-based DNS server commonly used in Kubernetes clusters for service and workload name resolution.

This explainer was generated by Manning's knowledge graph from the text of ASP.NET Core in Action, 3e. The section links point to the parts of the book it draws on.