Too many open files!

[Éric Allard]

We often get a lot of "ns_resp:TCP truncated:" in our log until we get
a "Too many open files". When we obtain this "Too many open files",
the server doesn't answer for a while. I know that happen when we got
an answer that was too large to fit into a DNS/TCP answer but I don't
know how I can provide my server from this problem!

Here my fd configuration on Solaris 8 in my /etc/system
* file descriptor
set rlim_fd_cur=2048
set rlim_fd_max=4096

Here a sample of my log file (/var/log/namedlog)

Mar 13 12:03:00 alexis last message repeated 11 times
Mar 13 12:03:01 alexis named[3532]: [ID 295310 local0.error] ns_resp:
TCP truncated:
  "42.220.218.216.in-addr.arpa" IN PTR from [216.218.220.42].53
Mar 13 12:03:01 alexis named[3532]: [ID 295310 local0.info] Lame server
on '221.77.1
58.64.in-addr.arpa' (in '77.158.64.in-addr.arpa'?): [64.159.80.3].53
'ns2.city-guide
.com': learnt (A=210.132.100.101,NS=209.244.0.1)
Mar 13 12:03:02 alexis named[3532]: [ID 295310 local0.error] ns_resp:
TCP truncated:
  "42.220.218.216.in-addr.arpa" IN PTR from [216.218.220.42].53
Mar 13 12:03:02 alexis named[3532]: [ID 295310 local0.notice] fcntl(fd,
F_DUPFD, 20)
: Too many open files
Mar 13 12:03:02 alexis named[3532]: [ID 295310 local0.error] ns_resp:
TCP truncated:
  "42.220.218.216.in-addr.arpa" IN PTR from [216.218.220.42].53
Mar 13 12:03:02 alexis named[3532]: [ID 295310 local0.notice] fcntl(fd,
F_DUPFD, 20)
: Too many open files
Mar 13 12:03:03 alexis named[3532]: [ID 295310 local0.info] Lame server
on '14.69.15
5.141.in-addr.arpa' (in '155.141.in-addr.arpa'?): [199.45.45.14].53
'NSDC.BA-DSG.NET
': learnt (A=192.5.6.30,NS=192.33.14.32)
Mar 13 12:03:03 alexis named[3532]: [ID 295310 local0.info] Lame server
on '14.69.15
5.141.in-addr.arpa' (in '155.141.in-addr.arpa'?): [141.151.0.68].53
'GTEPH.BA-DSG.NE
T': learnt (A=192.5.6.30,NS=192.33.14.32)
Mar 13 12:03:03 alexis named[3532]: [ID 295310 local0.error] ns_resp:
TCP truncated:
  "42.220.218.216.in-addr.arpa" IN PTR from [216.218.220.42].53
Mar 13 12:03:03 alexis last message repeated 1 time
Mar 13 12:03:03 alexis named[3532]: [ID 295310 local0.notice] fcntl(fd,
F_DUPFD, 20)
: Too many open files
Mar 13 12:03:03 alexis named[3532]: [ID 295310 local0.error] ns_resp:
TCP truncated:
  "42.220.218.216.in-addr.arpa" IN PTR from [216.218.220.42].53
Mar 13 12:03:04 alexis named[3532]: [ID 295310 local0.notice] fcntl(fd,
F_DUPFD, 20)
: Too many open files

Any hints will be gracefull!
Thanks!