Domain Name System ------------------------------------------- The Domain Name System (DNS) is a hierarchical naming system for computers, services, or any resource participating in the Internet. It associates various information with domain names assigned to each of the participants. Most importantly, it translates domain names meaningful to humans into the numerical (binary) identifiers associated with networking equipment for the purpose of locating and addressing these devices world-wide. An often used analogy to explain the Domain Name System is that it serves as the "phone book" for the Internet by translating human-friendly computer hostnames into IP addresses. For example, www.example.com translates to 208.77.188.166. For more information on DNS - http://en.wikipedia.org/wiki/Domain_Name_System U-Boot and DNS ------------------------------------------ CONFIG_CMD_DNS - controls if the 'dns' command is compiled in. If it is, it will send name lookups to the dns server (env var 'dnsip') Turning this option on will about abou 1k to U-Boot's size. Example: bfin> print dnsip dnsip=192.168.0.1 bfin> dns www.google.com 66.102.1.104 By default, dns does nothing except print the IP number on the default console - which by itself, would be pretty useless. Adding a third argument to the dns command will use that as the environment variable to be set. Example: bfin> print googleip ## Error: "googleip" not defined bfin> dns www.google.com googleip 64.233.161.104 bfin> print googleip googleip=64.233.161.104 bfin> ping ${googleip} Using Blackfin EMAC device host 64.233.161.104 is alive In this way, you can lookup, and set many more meaningful things. bfin> sntp ntpserverip not set bfin> dns pool.ntp.org ntpserverip 72.18.205.156 bfin> sntp Date: 2009-07-18 Time: 4:06:57 For some helpful things that can be related to DNS in U-Boot, look at the top level README for these config options: CONFIG_CMD_DHCP CONFIG_BOOTP_DNS CONFIG_BOOTP_DNS2