server can't find www.yahoo.com: SERVFAIL

[tuananh]

Hi,
 
My dns have responsed "server can't find www.yahoo.com
<http://www.yahoo.com/> " for a day.
 
This is status of my server:
Redhat(kernel 2.6) running on DELL 4600 ( 1CPUs + 2GB Mem) , BIND
9.2.4-2
Tasks:  56 total,   1 running,  55 sleeping,   0 stopped,   0 zombie
Cpu(s):  4.3% us,  2.0% sy,  0.0% ni, 90.7% id,  2.8% wa,  0.2% hi,
0.0% si
Mem:   2074952k total,  1677996k used,   396956k free,   106752k buffers
Swap:  2097144k total,      144k used,  2097000k free,  1227308k cached
 
I tried to dig, but
 
[root at dns1 setup]# dig www.yahoo.com
 
; <<>> DiG 9.2.4 <<>> www.yahoo.com
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 50600
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
 
;; QUESTION SECTION:
;www.yahoo.com.                 IN      A
 
;; Query time: 1292 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Tue Apr  4 16:33:25 2006
;; MSG SIZE  rcvd: 31
 
[root at dns1 setup]# dig +trace www.yahoo.com
 
; <<>> DiG 9.2.4 <<>> +trace www.yahoo.com
;; global options:  printcmd
.                       375024  IN      NS      I.ROOT-SERVERS.NET.
.                       375024  IN      NS      J.ROOT-SERVERS.NET.
.                       375024  IN      NS      K.ROOT-SERVERS.NET.
.                       375024  IN      NS      L.ROOT-SERVERS.NET.
.                       375024  IN      NS      M.ROOT-SERVERS.NET.
.                       375024  IN      NS      A.ROOT-SERVERS.NET.
.                       375024  IN      NS      B.ROOT-SERVERS.NET.
.                       375024  IN      NS      C.ROOT-SERVERS.NET.
.                       375024  IN      NS      D.ROOT-SERVERS.NET.
.                       375024  IN      NS      E.ROOT-SERVERS.NET.
.                       375024  IN      NS      F.ROOT-SERVERS.NET.
.                       375024  IN      NS      G.ROOT-SERVERS.NET.
.                       375024  IN      NS      H.ROOT-SERVERS.NET.
;; Received 436 bytes from 127.0.0.1#53(127.0.0.1) in 1 ms
 
com.                    172800  IN      NS      D.GTLD-SERVERS.NET.
com.                    172800  IN      NS      E.GTLD-SERVERS.NET.
com.                    172800  IN      NS      F.GTLD-SERVERS.NET.
com.                    172800  IN      NS      G.GTLD-SERVERS.NET.
com.                    172800  IN      NS      H.GTLD-SERVERS.NET.
com.                    172800  IN      NS      I.GTLD-SERVERS.NET.
com.                    172800  IN      NS      J.GTLD-SERVERS.NET.
com.                    172800  IN      NS      K.GTLD-SERVERS.NET.
com.                    172800  IN      NS      L.GTLD-SERVERS.NET.
com.                    172800  IN      NS      M.GTLD-SERVERS.NET.
com.                    172800  IN      NS      A.GTLD-SERVERS.NET.
com.                    172800  IN      NS      B.GTLD-SERVERS.NET.
com.                    172800  IN      NS      C.GTLD-SERVERS.NET.
;; Received 503 bytes from 192.36.148.17#53(I.ROOT-SERVERS.NET) in 182
ms
 
yahoo.com.              172800  IN      NS      ns1.yahoo.com.
yahoo.com.              172800  IN      NS      ns2.yahoo.com.
yahoo.com.              172800  IN      NS      ns3.yahoo.com.
yahoo.com.              172800  IN      NS      ns4.yahoo.com.
yahoo.com.              172800  IN      NS      ns5.yahoo.com.
;; Received 201 bytes from 192.31.80.30#53(D.GTLD-SERVERS.NET) in 266 ms
 
www.yahoo.com.          300     IN      CNAME   www.yahoo.akadns.net.
.                       3600000 IN      NS      A.ROOT-SERVERS.net.
.                       3600000 IN      NS      B.ROOT-SERVERS.net.
.                       3600000 IN      NS      C.ROOT-SERVERS.net.
.                       3600000 IN      NS      D.ROOT-SERVERS.net.
.                       3600000 IN      NS      E.ROOT-SERVERS.net.
.                       3600000 IN      NS      F.ROOT-SERVERS.net.
.                       3600000 IN      NS      G.ROOT-SERVERS.net.
.                       3600000 IN      NS      H.ROOT-SERVERS.net.
.                       3600000 IN      NS      I.ROOT-SERVERS.net.
.                       3600000 IN      NS      J.ROOT-SERVERS.net.
.                       3600000 IN      NS      K.ROOT-SERVERS.net.
.                       3600000 IN      NS      L.ROOT-SERVERS.net.
.                       3600000 IN      NS      M.ROOT-SERVERS.net.
;; Received 273 bytes from 66.218.71.63#53(ns1.yahoo.com) in 208 ms
 
I'm confusing, please help,
 
Thanks in advance,
TuanAnh.