1*1a32bf41SRobin GetzDomain Name System 2*1a32bf41SRobin Getz------------------------------------------- 3*1a32bf41SRobin Getz 4*1a32bf41SRobin GetzThe Domain Name System (DNS) is a hierarchical naming system for computers, 5*1a32bf41SRobin Getzservices, or any resource participating in the Internet. It associates various 6*1a32bf41SRobin Getzinformation with domain names assigned to each of the participants. Most 7*1a32bf41SRobin Getzimportantly, it translates domain names meaningful to humans into the numerical 8*1a32bf41SRobin Getz(binary) identifiers associated with networking equipment for the purpose of 9*1a32bf41SRobin Getzlocating and addressing these devices world-wide. An often used analogy to 10*1a32bf41SRobin Getzexplain the Domain Name System is that it serves as the "phone book" for the 11*1a32bf41SRobin GetzInternet by translating human-friendly computer hostnames into IP addresses. 12*1a32bf41SRobin GetzFor example, www.example.com translates to 208.77.188.166. 13*1a32bf41SRobin Getz 14*1a32bf41SRobin GetzFor more information on DNS - http://en.wikipedia.org/wiki/Domain_Name_System 15*1a32bf41SRobin Getz 16*1a32bf41SRobin GetzU-Boot and DNS 17*1a32bf41SRobin Getz------------------------------------------ 18*1a32bf41SRobin Getz 19*1a32bf41SRobin GetzCONFIG_CMD_DNS - controls if the 'dns' command is compiled in. If it is, it 20*1a32bf41SRobin Getz will send name lookups to the dns server (env var 'dnsip') 21*1a32bf41SRobin Getz Turning this option on will about abou 1k to U-Boot's size. 22*1a32bf41SRobin Getz 23*1a32bf41SRobin Getz Example: 24*1a32bf41SRobin Getz 25*1a32bf41SRobin Getzbfin> print dnsip 26*1a32bf41SRobin Getzdnsip=192.168.0.1 27*1a32bf41SRobin Getz 28*1a32bf41SRobin Getzbfin> dns www.google.com 29*1a32bf41SRobin Getz66.102.1.104 30*1a32bf41SRobin Getz 31*1a32bf41SRobin Getz By default, dns does nothing except print the IP number on 32*1a32bf41SRobin Getz the default console - which by itself, would be pretty 33*1a32bf41SRobin Getz useless. Adding a third argument to the dns command will 34*1a32bf41SRobin Getz use that as the environment variable to be set. 35*1a32bf41SRobin Getz 36*1a32bf41SRobin Getz Example: 37*1a32bf41SRobin Getz 38*1a32bf41SRobin Getzbfin> print googleip 39*1a32bf41SRobin Getz## Error: "googleip" not defined 40*1a32bf41SRobin Getzbfin> dns www.google.com googleip 41*1a32bf41SRobin Getz64.233.161.104 42*1a32bf41SRobin Getzbfin> print googleip 43*1a32bf41SRobin Getzgoogleip=64.233.161.104 44*1a32bf41SRobin Getzbfin> ping ${googleip} 45*1a32bf41SRobin GetzUsing Blackfin EMAC device 46*1a32bf41SRobin Getzhost 64.233.161.104 is alive 47*1a32bf41SRobin Getz 48*1a32bf41SRobin Getz In this way, you can lookup, and set many more meaningful 49*1a32bf41SRobin Getz things. 50*1a32bf41SRobin Getz 51*1a32bf41SRobin Getzbfin> sntp 52*1a32bf41SRobin Getzntpserverip not set 53*1a32bf41SRobin Getzbfin> dns pool.ntp.org ntpserverip 54*1a32bf41SRobin Getz72.18.205.156 55*1a32bf41SRobin Getzbfin> sntp 56*1a32bf41SRobin GetzDate: 2009-07-18 Time: 4:06:57 57*1a32bf41SRobin Getz 58*1a32bf41SRobin Getz For some helpful things that can be related to DNS in U-Boot, 59*1a32bf41SRobin Getz look at the top level README for these config options: 60*1a32bf41SRobin Getz CONFIG_CMD_DHCP 61*1a32bf41SRobin Getz CONFIG_BOOTP_DNS 62*1a32bf41SRobin Getz CONFIG_BOOTP_DNS2 63