I'm using ClearOS (based on CentOS, so any info specific to it should apply here) as a gateway, DHCP, and DNS server. I had this server running perfectly for a month or two before replacing it with another server. However due DNS and DHCP failing 2 days in and a host of other performance issues (the box was a little underpowered), I changed back to the origional server. However 2 days in DHCP and DNS are failing again, and I'm out of idea's on why.

In both cases to my knowledge no network or server changes occurred after installation. Right after installing (and at least a day in) DNS and DHCP was working just fine. However later (Day 2) I get a call saying their internet is down (translation: Nobody can get to websites because DNS is down)

I've tried to fix the problem by checking if the dnsmasq is even running (it is), restarting the service, and restarting the server to no effect. I do have two internal servers that have static DHCP leases but one's lease must of expired as I can't connect to it anymore. I'm hesitant to do any dhcp testing on the last server as I'll not be able to connect to it anymore.

Is there anything anyone can think of on why DNS and DHCP would fail 2 days in to running perfectly?

More info:

Running dnsmasq in debug mode. This is all that's displayed even when running nslookup quackwall. I'm not sure though if nslookup commands should show up in the log

[root@quackwall ~]# /usr/sbin/dnsmasq -dq
dnsmasq: started, version 2.49 cachesize 150
dnsmasq: compile time options: IPv6 GNU-getopt no-DBus no-I18N DHCP TFTP
dnsmasq-dhcp: DHCP, IP range 10.0.0.100 -- 10.0.0.254, lease time 12h
dnsmasq: reading /etc/resolv.conf
dnsmasq: using nameserver 74.128.17.114#53
dnsmasq: using nameserver 74.128.19.102#53
dnsmasq: read /etc/hosts - 5 addresses
dnsmasq-dhcp: read /etc/ethers - 2 addresses

On the other server DNS and the Gateway are all configured correctly (10.0.0.2 is quackwall)

lordquackstar@quackgame:~$ netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
10.0.0.0        0.0.0.0         255.255.240.0   U         0 0          0 eth0
0.0.0.0         10.0.0.2        0.0.0.0         UG        0 0          0 eth0
lordquackstar@quackgame:~$ cat /etc/resolv.conf
nameserver 10.0.0.2
domain highwow.lan
search highwow.lan