limit files set to fdlimit

[bind_ml2 at telusquebec.net]

We have bind 8.2.7-REL on a solaris 8. November 18 and 19, our DNS =
stopped
answering and I found the following message in the named log:
limit files set to fdlimit (1024)

I did a pfiles and saw a lot of this kind of records (something like =
1000
records):

148: S_IFSOCK mode:0666 dev:229,0 ino:60560 uid:0 gid:0 size:0
       O_RDWR|O_NONBLOCK FD_CLOEXEC
        sockname: AF_INET =85

I know that means too much descriptors opened but why named opens so =
much
Sockets?
Why did this happened?
How can I resolve it?

P.S.:I couldn=92t start the debug because I have too much traffic on =
this
server.

Thanks!

Eric