DHCP questions cover server configuration, relay agents (ip helper-address), DHCP snooping, and the four-step DORA handshake. Common exam scenarios: a host isn't getting an IP, a relay agent isn't forwarding requests, or a rogue DHCP server is handing out wrong addresses.
Start Scenario PracticeYou want to improve profiling accuracy for endpoints that do not send DHCP options. You decide to use SNMP Trap profiling. What is a critical prerequisite for this to function?
Explanation: SNMP Trap profiling requires the network device (switch, WLC, router) to be configured to send SNMP traps to the ISE PSN's IP address, because ISE relies on receiving those traps to extract endpoint attributes like MAC addresses, link up/down events, and CDP/LLDP neighbor data. Without the device actively sending traps to ISE, the SNMP Trap probe receives no data and profiling cannot occur.
You are troubleshooting a device that is stuck in the 'Unknown' profile state. You have confirmed that the DHCP probe is receiving packets. What is the next logical step to investigate the failure?
Explanation: When an endpoint is stuck in 'Unknown' despite the DHCP probe receiving packets, the next step is to inspect the endpoint's attributes in Context Visibility to see what ISE actually learned from the probe — such as whether the DHCP class attribute or MAC OUI was populated. This reveals whether the probe data is being parsed correctly or if a profiling condition is failing to match.
You are configuring a DHCP probe on a Cisco ISE node to identify endpoints. Which specific configuration step is required to ensure the ISE node receives DHCP traffic when the client and server are on a different subnet?
Explanation: To ensure the ISE node receives DHCP traffic when the client and DHCP server are on different subnets, you must configure an IP helper-address on the Layer 3 device (e.g., router or switch) for the client VLAN, pointing to the ISE node. This relays DHCP packets to ISE, allowing the DHCP probe to collect profiling data. Thus, option C is correct.
Which TWO of the following are necessary to correctly configure a custom profiling condition based on DHCP attributes?
Explanation: Option C is correct because a profiling condition must specify a matching operator (such as equals, contains, starts with, or matches regex) that determines how the collected DHCP attribute value is compared against the configured value. Option E is correct because the condition must reference a valid DHCP attribute from the available attribute list (for example, DHCP Option 12 hostname, Option 60 vendor class identifier, or Option 55 parameter request list) so the profiler knows which DHCP field to evaluate. Together, selecting the DHCP attribute and defining its matching operator are the two essential components of a custom DHCP-based profiling condition. Option A is not required because HTTP profiling is a separate profiling method used for HTTP User-Agent attributes, not DHCP. Option B is not required because DHCP profiling relies on the DHCP request/response exchange and does not depend on the endpoint having a static IP. Option D is not required because clearing the switch MAC address table is unrelated to defining a profiling condition and would not affect DHCP attribute matching.
A network administrator is configuring Cisco ISE profiling for a new branch office. The administrator wants to ensure that endpoints are profiled based on information collected from DHCP packets. Which probe must be enabled on the Policy Service node to collect DHCP attributes?
Explanation: The DHCP probe is specifically designed to capture DHCP packets and extract attributes like hostname, vendor class, and requested parameters. These attributes are then used by the profiling engine to classify endpoints. For profiling based on DHCP information, enabling the DHCP probe on the Policy Service node is required.
DHCP questions cover server configuration, relay agents (ip helper-address), DHCP snooping, and the four-step DORA handshake. Common exam scenarios: a host isn't getting an IP, a relay agent isn't forwarding requests, or a rogue DHCP server is handing out wrong addresses. These appear throughout the SISE and require you to apply your knowledge, not just recall facts.
Cisco doesn't publish an exact breakdown, but scenario-based questions (especially exhibit and command-output formats) make up a significant portion of the SISE. Practicing each scenario type ensures you're ready for any format.
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