dhcp server problem

[shellarchive]

we have dhcp server configured on rhel3es serving approx 100 windows clients

following is the configuration file,

ddns-update-style interim;
ignore client-updates;
authoritative;
option domain-name "india.airtel.itm";
option domain-name-servers 10.56.40.15,10.56.40.16;
subnet 10.57.12.0 netmask 255.255.254.0 {
        range 10.57.12.5 10.57.13.119;
        range 10.57.13.121 10.57.13.253;
        option routers 10.57.12.1;
        option subnet-mask 255.255.254.0;
        option time-offset -18000;
        default-lease-time 259200;
        max-lease-time 259200;

host Ambrish_Sales_06{
        hardware ethernet 00:0d:60:6b:ba:5c;
        fixed-address 10.57.12.223;
        }
host b0016824{
        hardware ethernet 00:24:e8:f0:f2:16;
        fixed-address 10.57.13.235;
        }
host b0009336{
        hardware ethernet 00:16:41:16:cb:07;
        fixed-address 10.57.12.178;
        }
host B0021991{
        hardware ethernet 00:1e:37:8e:0c:7d;
        fixed-address 10.57.13.151;
        }
}

we have done mac id binding for most of the ips,
dhcp server many times fails to assing bindind ip to the client,

/var/log/messages gives the following errors,

Apr 28 03:17:03 dhcpmum dhcpd: DHCPREQUEST for 10.57.13.235 (10.57.13.120) from 00:24:e8:f0:f2:16 via 10.57.12.3
Apr 28 03:17:03 dhcpmum dhcpd: from the dynamic address pool for 10.57.12/23
Apr 28 03:17:03 dhcpmum dhcpd: Remove host declaration b0016824 or remove 10.57.13.235
Apr 28 03:17:03 dhcpmum dhcpd: Dynamic and static leases present for 10.57.13.235.

Apr 28 00:56:17 dhcpmum dhcpd: DHCPREQUEST for 10.57.12.168 from 00:01:6c:99:56:b9 via eth0
Apr 28 00:56:17 dhcpmum dhcpd: from the dynamic address pool for 10.57.12/23
Apr 28 00:56:17 dhcpmum dhcpd: Remove host declaration training1 or remove 10.57.12.168
Apr 28 00:56:17 dhcpmum dhcpd: Dynamic and static leases present for 10.57.12.168.
Apr 27 23:43:02 dhcpmum dhcpd: DHCPREQUEST for 10.57.12.72 from 00:11:25:70:c9:2b via eth0
Apr 27 23:43:02 dhcpmum dhcpd: from the dynamic address pool for 10.57.12/23
Apr 27 23:43:02 dhcpmum dhcpd: Remove host declaration myank or remove 10.57.12.72
Apr 27 23:43:02 dhcpmum dhcpd: Dynamic and static leases present for 10.57.12.72.

Apr 27 23:35:30 dhcpmum dhcpd: DHCPREQUEST for 10.57.28.124 from 00:12:f0:44:42:d9 (gaurang_6th_mkt) via 10.57.28.2
Apr 27 23:35:30 dhcpmum dhcpd: Unable to add forward map from gaurang_6th_mkt.india.airtel.itm to 10.57.28.124: DNS format er
ror

this messages is repeated for most of the ips for which we done mac binding.

any help ! ! !

i have shown selected text of messages & dhcpd configuration file.

[rcgreen]

The addresses you want to use as fixed addresses should
be outside the range stated for dynamic address allocation.

 range 10.57.12.5 10.57.13.119;
        range 10.57.13.121 10.57.13.253;

that is, outside these ranges