DHCP keeps "dropping out" or resetting?

[DAVID RICHWALSKI]

Hi.. I have a Cisco 2851 Router and I have DHCP configured... but it keeps " dropping out" or resetting...(Best way to describe it) 

ip dhcp conflict logging

ip excluded-address 192.168.0.1 192.168.0.15

ip dhcp excluded-address 192.168.0.30
ip dhcp excluded-address 192.168.0.50
ip dhcp excluded-address 192.168.0.100
ip dhcp excluded-address 192.168.0.101
!
ip dhcp pool xxxxxxx
network 192.168.0.0 255.255.255.0
default-router 192.168.0.50
netbios-node-type h-node
domain-name xxxxxx
dns-server 71.10.216.1 4.2.2.2 71.10.216.2 1.1.1.1 209.18.47.61
lease 0 7

[MHM Cisco World]

what is drop ?

[DAVID RICHWALSKI]

hi... my DHCP just stops giving out addresses... so I have to log in to the Router and issue the "service dhcp" command.. save the config... reboot and then it works again... for awhile... I am baffled?? 

[MHM Cisco World]

show ip dhcp binding 
show ip dhcp pool
share both output here 

[DAVID RICHWALSKI]

stinger#sh ip dhcp binding
Bindings from all pools not associated with VRF:
IP address Client-ID/ Lease expiration Type
Hardware address/
User name
192.168.0.16 5cad.76d2.7a9b Jul 25 2022 04:32 PM Automatic
stinger#sh ip dhcp pool

Pool scorpion :
Utilization mark (high/low) : 100 / 0
Subnet size (first/next) : 0 / 0
Total addresses : 254
Leased addresses : 1
Pending event : none
1 subnet is currently in the pool :
Current index IP address range Leased addresses
192.168.0.17 192.168.0.1 - 192.168.0.254 1
stinger#

[MHM Cisco World]

the subnet give 254 (include the lease one)
and there is no exclude IP in show ip dhcp pool !!!
I think it is bug but 
ip excluded-address not ip dhcp excluded-address ?
so correct this command 
and try add the dhcp exclude range again.
if not solve try add it IP by IP.

[DAVID RICHWALSKI]

under the "pool" I tried ip excluded-address... and it is invalid... I then under the "pool" I tried the ip dhcp excluded-address and it moves it "outside" of the "pool" just like my original config.

I tried to enter the subnet under the "pool" and it was invalid.. also outside the "pool" was invalid

[MHM Cisco World]

IP dhcp exclude is config in global not under POOL.
after you add 
ip dhcp exclude 
do 
show ip dhcp pool
do you see the exclude line ?

[MHM Cisco World]

I do small lab for you,
you see the excluded address line appear.

[marce1000]

                   >.... but it keeps " dropping out" or resetting..

  Provide logs of what you mean by that or else screenshots of the phenomena you are observing.  In general do not use routers or switches for dhcp services but separate appliances , much better, it avoids race conditions when providing network services to clients.

 M.

[Georg Pauwen]

Hello,

do you have 'ip subnet-zero' configured ? It should be enabled by default in any newer (>12.x) IOS release, but it might be worth checking anyway...

[Richard Burts]

Is logging enabled on this router? We would be most interested in logging buffered, but would be good to know about each type of logging. If so what severity level is specified? When the issue develops, can you check the logs and see if there are any log messages that might relate to DHCP?

Worst case you might want to run debug for DHCP and monitor the output until the issue occurs.