1Domain Name System 2------------------------------------------- 3 4The Domain Name System (DNS) is a hierarchical naming system for computers, 5services, or any resource participating in the Internet. It associates various 6information with domain names assigned to each of the participants. Most 7importantly, it translates domain names meaningful to humans into the numerical 8(binary) identifiers associated with networking equipment for the purpose of 9locating and addressing these devices world-wide. An often used analogy to 10explain the Domain Name System is that it serves as the "phone book" for the 11Internet by translating human-friendly computer hostnames into IP addresses. 12For example, www.example.com translates to 208.77.188.166. 13 14For more information on DNS - http://en.wikipedia.org/wiki/Domain_Name_System 15 16U-Boot and DNS 17------------------------------------------ 18 19CONFIG_CMD_DNS - controls if the 'dns' command is compiled in. If it is, it 20 will send name lookups to the dns server (env var 'dnsip') 21 Turning this option on will about abou 1k to U-Boot's size. 22 23 Example: 24 25bfin> print dnsip 26dnsip=192.168.0.1 27 28bfin> dns www.google.com 2966.102.1.104 30 31 By default, dns does nothing except print the IP number on 32 the default console - which by itself, would be pretty 33 useless. Adding a third argument to the dns command will 34 use that as the environment variable to be set. 35 36 Example: 37 38bfin> print googleip 39## Error: "googleip" not defined 40bfin> dns www.google.com googleip 4164.233.161.104 42bfin> print googleip 43googleip=64.233.161.104 44bfin> ping ${googleip} 45Using Blackfin EMAC device 46host 64.233.161.104 is alive 47 48 In this way, you can lookup, and set many more meaningful 49 things. 50 51bfin> sntp 52ntpserverip not set 53bfin> dns pool.ntp.org ntpserverip 5472.18.205.156 55bfin> sntp 56Date: 2009-07-18 Time: 4:06:57 57 58 For some helpful things that can be related to DNS in U-Boot, 59 look at the top level README for these config options: 60 CONFIG_CMD_DHCP 61 CONFIG_BOOTP_DNS 62 CONFIG_BOOTP_DNS2 63