Tag Archives: DNS

  • Resolver Cache – Linux vs Windows

    Microsoft Windows OS’ have a resolver cache built into the actual OS.  Most Windows admins already know this.  When your Windows system performs a DNS query the results are stored by the OS and are available for use by other applications and processes running on the system.  This means that you can resolve www.itdojo.com to its IP address using Firefox and then open a command prompt and ping www.itdojo.com without your system performing a new DNS query in support of the ping.  The ping command will use the cached entry stored by the OS.  For Windows systems you can view and control (somewhat) this using these commands:

  • Basic IPv6 Resolver Configuration in Ubuntu

    Most DNS servers these days are glad to resolve IPv6 addresses from clients who send the queries packaged in IPv4 packets.  In the grand scheme of things the DNS servers don’t care how you sent the question, they just care about the question.  And because almost everybody still relies heavily upon IPv4, most of us who are trying to push toward IPv6 have been satisfied to get our AAAA resolutions using IPv4 as the transport.  But if you want to start being more ‘pure’ in your IPv6 deployments you need to give your system the ability to not only send IPv6 packets out into the Internet, you also need to learn where it is you are going via IPv6 as well.  Put plainly, you need to configure your system to get its IPv6 name resolution using IPv6 packets.

  • Delivering DNS via IPv6 Router Advertisements

    One very cool and highly promoted feature of IPv6 is stateless address autoconfiguration.  If you don’t already know, this feature enables a node to automatically derive its IPv6 address(es) without the help of of a DHCP server.  That is a big departure from the world of IPv4.  In IPv4 you either had to manually configure your IP addresses or you had to use DHCP.  IPv6 has added address autoconfiguration as a third (and typically default) option.