CCNA 5.4: Troubleshoot client- and router-based DHCP connectivity issues
Client and router based DHCP connectivity issues can be the result of any number of issues, but most often it is due to a misconfiguration.
- Client and router based DHCP connectivity issues are typically the result of misconfigurations.
- Has the DHCP lease expired?
- If the lease has expired and another client is assigned the IP, their could be duplicate IPs on the network causing a conflict. Use the show ip dhcp conflict command to detect.
- When dhcp conflicts are detected, the address is removed from the pool until an administrator resolves the issue.
- Can the client get to the DHCP server?
- Troubleshoot networking issues. Check vlans, switchports, cabling and configurations.
- Set a static IP on the client and test by pinging the DHCP server (the router). If the client can't ping the DHCP server, troubleshoot the networking more. If the client can ping the DHCP server, the issue is most likely with the DHCP server.
- Is the issue with the DHCP server?
- In this case, the DHCP server is running on the router.
- If the client can ping the DHCP server, verify the DHCP configuration on the router is correct.
- Is the issue with the DHCP relay?
- Remove the relay from the equation by setting up the client on the same subnet as the DHCP server. If it gets assigned an address on the directly connected subnet than the issue points to the relay agent.
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