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  7 misunderstandings of DNS resolution

DNS resolution is generally considered as providing mapping between domain name and IP address, for example www.google.com maps to 74.125.71.103. There are two important reasons for doing DNS resolution: IP address is hard to remember, while domain name is human friendly Virtual host may access different contents according to the header of the host domain name(sub-domain name) Some webmasters may have some unreasonable requirements when doing DNS resolution. It mainly because they are not very...

   DNS resolution,misunderstanding     2012-10-20 12:57:16

  Configure static IP for Linux

When a Linux server is running, it has to have an IP so that other machines can talk to it. It is often desired that the server would own a static IP so that every time other machines want to connect to it, the same IP address would be used. This is extremely useful when there are virtual machines installed on a host machine where the virtual machine would start and stop now and then.  To configure static IP address for a Linux server, the /etc/network/interfaces needs to be updated. Assumi...

   LINUX,NETWORK,STATIC IP,DNS     2017-07-08 08:39:58

  How DNS lookup works

When accessing a website, a domain name would be needed normally. To get to the actual web server, the domain name must be mapped to an actual IP address and the IP address will be used to reach the web server. The process of finding the IP address from a domain name is called DNS lookup.  How does DNS lookup work? There are tons of domain name and IP address around the world, there must be some well-designed architecture to support fast lookup. This post will explain how this works. DNS Se...

   DNS,DNS LOOKUP     2022-09-09 23:11:03

  Handle NXDomain error when resolving IP address in Ruby DNS resolver

In another post, we covered how to resolve SystemStackError when resolving IP address in Ruby. In this post, we would cover another common issue where a NXDomain error is returned when resolving an IP address. The NXDomain error means that the queried domain name does not exist in the DNS. In Ruby, DNS resolver library will use /etc/resolv.conf by default get the name servers to resolve the domain name. There are multiple DNS name servers can be specified in /etc/resolv.conf with below format. ...

   RUBY,RUBY ON RAILS,NETWORK,DNS,NXDOMAIN     2017-07-16 01:39:23

  Resolve SystemStackError issue when resolving IP address in Ruby

In Ruby, Resolv is the default DNS resolution implementation. It can be used to resolve IP address of a hostname. To use it, one just needs to require 'resolv' in the code. But sometimes, a user would want to check /etc/hosts first or some other mechanisms to resolve an IP address. In this case, one can require 'resolv-replace' and then replace the default DNS resolvers with customized DNS resolvers. For example, using resolv-replace, one would write require 'resolv-replace' Resolv::DefaultResol...

   RUBY,RUBY ON RAILS,NETWORK     2017-07-08 09:54:35

  Get Facebook, Twitter and YouTube back

Facebook, Twitter and YouTube have become part of many people's daily network life. People hang around these sites to network with known and unknown friends, to know about the latest news and to relax with fancy video clips. But what will you feel if all of a sudden you cannot access them? Want to experience this? Go behind the GFW(Great Firewall) of China. Just a joke, but it's real. Huh, you are out of China? Don't worry. Change your DNS server to those located in China. I just experienced it,...

   DNS spoofing, GFW, YouTube, 37.61.54.158     2014-12-20 21:41:34

  gethostbyname vs getaddrinfo

getaddrinfo is slower than ping when resolving domain names. I think ping uses gethostbyname to resolve a domain name. The question becomes whether getaddrinfo is slower than gethostbyname. After testing with both functions, we find that getaddrinfo is really slow compared to gethostbyname. By strace tracking,  we find getaddrinfo will communicate with DNS server 10 times and gethostbyname will communicate with DNS server communication twice.gethostbyname is an old way to resolve domain nam...

   C++,network,DNS     2012-08-15 14:06:34

  12 useful Chrome commands

Many useful features of Chrome don't show up on its menus. You can access them through the chrome:// command. In this article we will introduce 12 useful chrome:// commands. 1. chrome://flags It can be used to turn on or turn off some chrome features. 2. chrome://dns This command will show the domain name list caught by the browser. 3. chrome://downloads You can access this through chrome menu as well. The shortcut is Ctrl+J 4. chrome://extensions This command equals to Menu->Tools->Ext...

   Chrome,chrome://     2013-01-25 04:38:03

  Subdomain Configuration

Subdomain ConfigurationA subdomain configuration is very similar to a domain name configuration. The only difference is that the subdomain entry is tied to the corresponding domain name lookup. A request for the subdomain (e.g. http://content.websitegear.com) will be routed to a DNS server containing the DNS information for the parent domain (websitegear.com). Once the DNS record for the subdomain is resolved to a particular IP address, the request is sent to the web server listening on that IP ...

   Domain,Subdomain,Configuration,Setup     2011-10-09 09:23:16

  Taking Precautions to Avoid Shady VPN Providers

VPNs or virtual private networks are virtual tunnels that obscure your IP address, routing your internet traffic through a server located in a country of your choice, in an encrypted and anonymous way. Using a VPN allows you to: secure your sensitive data from hackers obscure the IP address so you can see content not available in your country avoid websites you routinely surf (e.g., Facebook) noticing a different IP address when you are traveling, and asking you to verify your identity bypass t...

   VPN,NETWORKING     2019-02-19 07:26:26

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