simple DNS question
Brad Knowles
brad.knowles at skynet.be
Sat Mar 17 13:26:55 UTC 2001
At 11:34 PM +0100 3/16/01, Ali Ghodsi wrote:
> My book says that the iterative DNS lookup is the most common one, how come?
> To me it just sounds like its much easier to do recursive since the DNS:es
> will handle all the requests.
Client programs will almost always be asking a caching recursive
nameserver, but these clients do not themselves generate the largest
number of queries. Indeed, it is the caching recursive nameservers
themselves that generate the largest number of queries, as they
iterate through the answers returned by the other nameservers in the
world, trying to answer the query that was asked of them in a
recursive manner.
So, in short, you are both right.
--
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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