simple DNS question

Brad Knowles brad.knowles at skynet.be
Sat Mar 17 14:05:17 UTC 2001


At 2:56 PM +0100 3/17/01, Ali Ghodsi wrote:

>  would my DNS server, if it cant resolve some name, ask the root directly?

	It could.

>                                                                             or
>  where in the hierarchy would it start.

	That depends on your configuration.  If you've got it configured 
to forward unknown queries to another machine, then that's what it 
would do.  If it was a straight caching recursive server, then it 
would pop one element off the domain name and see if it has any 
information for that.  It would keep popping off elements from the 
domain name until it finds something that it does already have some 
hints for, or until it arrives at an empty name (implied root 
domain), at which point it would go ask the root nameservers where 
(for example) information for ".org" can be found, it would then ask 
these machines where information for "fred.org" can be found, it 
would then ask those machines where information for "george.fred.org" 
can be found, etc....

>                                          You have forwarders configured in
>  your name servers, would it be step by step worked up the hierarchy, or
>  would it directly go to the root.

	If you're using forwarders, then the query would simply be 
forwarded to the machines that it's configured to forward queries to, 
and it wouldn't do anything else.

--
Brad Knowles, <brad.knowles at skynet.be>

/*     efdtt.c     Author:  Charles M. Hannum <root at ihack.net>             */
/*                                                                         */
/*     Thanks to Phil Carmody <fatphil at asdf.org> for additional tweaks.    */
/*                                                                         */
/*     Length:  434 bytes (excluding unnecessary newlines)                 */
/*                                                                         */
/*     Usage is:  cat title-key scrambled.vob | efdtt >clear.vob           */
/*     where title-key = "153 2 8 105 225" or other similar 5-byte key     */

#define m(i)(x[i]^s[i+84])<<
unsigned char x[5],y,s[2048];main(n){for(read(0,x,5);read(0,s,n=2048);write(1,s
,n))if(s[y=s[13]%8+20]/16%4==1){int i=m(1)17^256+m(0)8,k=m(2)0,j=m(4)17^m(3)9^k
*2-k%8^8,a=0,c=26;for(s[y]-=16;--c;j*=2)a=a*2^i&1,i=i/2^j&1<<24;for(j=127;++j<n
;c=c>y)c+=y=i^i/8^i>>4^i>>12,i=i>>8^y<<17,a^=a>>14,y=a^a*8^a<<6,a=a>>8^y<<9,k=s
[j],k="7Wo~'G_\216"[k&7]+2^"cr3sfw6v;*k+>/n."[k>>4]*2^k*257/8,s[j]=k^(k&k*2&34)
*6^c+~y;}}


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