Symptoms include devices failing to obtain IP addresses from the DHCP server, resulting in connectivity issues. You may also observe error logs or alerts on the router indicating that the DHCP address pool is exhausted. If you run 'show ip dhcp binding' on the router and see that all available addresses are assigned, this further confirms pool exhaustion.

You can determine the size of the DHCP pool by accessing the router's configuration and checking the DHCP pool settings. Use the command 'show ip dhcp pool [pool-name]' in the CLI, which will display the total number of addresses, the number of leased addresses, and the number of free addresses remaining in that pool.

To mitigate DHCP pool exhaustion, consider implementing address reservation for critical devices, increasing the pool size by modifying the subnet mask to allow for more IP addresses, or decreasing the lease time for dynamic addresses, which enables faster turnover. Additionally, segmenting the network using VLANs and running separate DHCP servers for each VLAN can reduce load on a single DHCP pool.

Network performance can suffer as devices continuously attempt DHCP discovery and timeout, leading to increased broadcast traffic and potential network congestion. Security can be compromised as unauthorized devices may exploit an exhausted DHCP pool, leading to rogue DHCP servers unintentionally being introduced into the network, which can result in Man-in-the-Middle attacks or loss of data integrity.

To enable DHCP snooping, access the router's command line interface and execute 'ip dhcp snooping' followed by 'ip dhcp snooping vlan [vlan-id]'. This feature limits DHCP responses to only trusted ports, helping to prevent unauthorized DHCP servers from allocating IP addresses from the pool and contributing to pool exhaustion issues. Always ensure to configure trusted ports with 'interface [interface-id]' followed by 'ip dhcp snooping trust' to complete the setup.