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 16 17 18U-Boot and DNS 19------------------------------------------ 20 21CONFIG_CMD_DNS - controls if the 'dns' command is compiled in. If it is, it 22 will send name lookups to the dns server (env var 'dnsip') 23 Turning this option on will about abou 1k to U-Boot's size. 24 25 Example: 26 27bfin> print dnsip 28dnsip=192.168.0.1 29 30bfin> dns www.google.com 3166.102.1.104 32 33 By default, dns does nothing except print the IP number on 34 the default console - which by itself, would be pretty 35 useless. Adding a third argument to the dns command will 36 use that as the environment variable to be set. 37 38 Example: 39 40bfin> print googleip 41## Error: "googleip" not defined 42bfin> dns www.google.com googleip 4364.233.161.104 44bfin> print googleip 45googleip=64.233.161.104 46bfin> ping ${googleip} 47Using Blackfin EMAC device 48host 64.233.161.104 is alive 49 50 In this way, you can lookup, and set many more meaningful 51 things. 52 53bfin> sntp 54ntpserverip not set 55bfin> dns pool.ntp.org ntpserverip 5672.18.205.156 57bfin> sntp 58Date: 2009-07-18 Time: 4:06:57 59 60 For some helpful things that can be related to DNS in U-Boot, 61 look at the top level README for these config options: 62 CONFIG_CMD_DHCP 63 CONFIG_BOOTP_DNS 64 CONFIG_BOOTP_DNS2 65