The answer is that the RADIUS server returned a VLAN ID that placed the port in a VLAN lacking connectivity to the default gateway. This is correct because 802.1X authorization succeeded—the port shows as 'authorized'—but the RADIUS server’s Access-Accept included a Tunnel-Private-Group-ID attribute that dynamically assigned the port to a VLAN without a routed SVI or with an incorrect subnet, isolating the workstation despite successful authentication. On the CCNA 200-301 v2 exam, this scenario tests your understanding of 802.1X VLAN assignment and the distinction between authentication success and network-layer connectivity; a common trap is assuming the issue is with authentication itself when the port is already authorized. Remember: authorized does not mean connected—the VLAN assignment must match a functional gateway. A helpful memory tip is “Auth is green, VLAN is the scene”—authentication only opens the door; the VLAN assignment determines whether you reach the network.
CCNA Network Services and Security Practice Question
This 200-301 practice question tests your understanding of network services and security. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Exhibit
Switch# show running-config interface GigabitEthernet1/0/1
Building configuration...
Current configuration : 250 bytes
!
interface GigabitEthernet1/0/1
switchport mode access
switchport access vlan 10
authentication port-control auto
authentication periodic
authentication timer reauthenticate 3600
dot1x pae authenticator
dot1x timeout tx-period 3
spanning-tree portfast
end
Switch# show authentication sessions interface GigabitEthernet1/0/1 details
Interface: GigabitEthernet1/0/1
MAC Address: aaaa.bbbb.cccc
IP Address: 192.168.10.25
User-Name: host/workstation
Status: Authz Success
Domain: DATA
Oper host mode: single-host
Oper control dir: both
Session timeout: 3600s
Common Session ID: 0A1B2C3D4E5F6G7H8I9J0K
Acct Session ID: 0x00000001
Handle: 0x00000001
Runnable methods list:
Method State
dot1x Authz Success
Switch# show dot1x all details
Sysauthcontrol ENABLED
Dot1x Protocol Version 3
Supplicant aaaa.bbbb.cccc, GigabitEthernet1/0/1
PAE = AUTHENTICATOR
quietPeriod = 60
serverTimeout = 30
maxReq = 2
reAuthMax = 2
allowAuthOn = [all]
startPeriod = 30
handshakePeriod = 15
txPeriod = 3
guestVlan = 999
authVlan = 100
criticalVlan = 200
hostMode = SINGLE_HOST
port-control = AUTO
control-direction = BOTH
host-auth = [success]
re-authentication = ENABLED
re-authperiod = 3600
server-timeout = 30
supp-timeout = 30
server-retries = 2
supp-retries = 2
max-reauth-req = 2
lastrx = 0
cap = 0
status = AUTHORIZED
state = HELD
backend-state = HELD
method = dot1x
timeout = 30
A network administrator has configured 802.1X port-based authentication on a Cisco IOS-XE switch for a new access port connected to a user workstation. The workstation is failing to gain network access. The switch port is in the 'authorized' state, but the workstation cannot ping the default gateway. The administrator checks the running configuration and the authentication session details. What is the most likely cause of the issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Switch# show running-config interface GigabitEthernet1/0/1
Building configuration...
Current configuration : 250 bytes
!
interface GigabitEthernet1/0/1
switchport mode access
switchport access vlan 10
authentication port-control auto
authentication periodic
authentication timer reauthenticate 3600
dot1x pae authenticator
dot1x timeout tx-period 3
spanning-tree portfast
end
Switch# show authentication sessions interface GigabitEthernet1/0/1 details
Interface: GigabitEthernet1/0/1
MAC Address: aaaa.bbbb.cccc
IP Address: 192.168.10.25
User-Name: host/workstation
Status: Authz Success
Domain: DATA
Oper host mode: single-host
Oper control dir: both
Session timeout: 3600s
Common Session ID: 0A1B2C3D4E5F6G7H8I9J0K
Acct Session ID: 0x00000001
Handle: 0x00000001
Runnable methods list:
Method State
dot1x Authz Success
Switch# show dot1x all details
Sysauthcontrol ENABLED
Dot1x Protocol Version 3
Supplicant aaaa.bbbb.cccc, GigabitEthernet1/0/1
PAE = AUTHENTICATOR
quietPeriod = 60
serverTimeout = 30
maxReq = 2
reAuthMax = 2
allowAuthOn = [all]
startPeriod = 30
handshakePeriod = 15
txPeriod = 3
guestVlan = 999
authVlan = 100
criticalVlan = 200
hostMode = SINGLE_HOST
port-control = AUTO
control-direction = BOTH
host-auth = [success]
re-authentication = ENABLED
re-authperiod = 3600
server-timeout = 30
supp-timeout = 30
server-retries = 2
supp-retries = 2
max-reauth-req = 2
lastrx = 0
cap = 0
status = AUTHORIZED
state = HELD
backend-state = HELD
method = dot1x
timeout = 30
A
The RADIUS server has not been configured with the correct shared secret, causing authentication to fail silently.
Why wrong: The show authentication sessions output shows 'Authz Success', meaning authentication and authorization succeeded. A shared secret mismatch would cause authentication failure, not a successful authorization.
B
The RADIUS server returned a VLAN ID that placed the port in a VLAN lacking connectivity to the default gateway, such as a VLAN without an SVI or incorrect subnet assignment.
After successful 802.1X authentication, the switch can dynamically assign the port to a VLAN specified in the RADIUS Access-Accept message. If that VLAN exists but is not the correct user VLAN—for example, a dead-end VLAN or a VLAN where the default gateway IP is not configured or reachable—the device will appear authorized but will be unable to reach the gateway, exactly matching the symptoms.
C
The switch port is in 'err-disabled' state due to a port-security violation, preventing any traffic.
Why wrong: The show command output clearly shows the port status as 'AUTHORIZED' and 'Authz Success'. There is no indication of err-disable. Port-security violations would show a different status.
D
The workstation's supplicant is not configured with the correct EAP method, causing the authentication to use the guest VLAN instead.
Why wrong: The output shows 'authVlan = 100' and the session is authorized with 'method = dot1x' and 'status = AUTHORIZED'. This indicates the supplicant successfully authenticated and was placed in the auth VLAN, not the guest VLAN.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The RADIUS server returned a VLAN ID that placed the port in a VLAN lacking connectivity to the default gateway, such as a VLAN without an SVI or incorrect subnet assignment.
The switch port is in the 'authorized' state, indicating that 802.1X authentication succeeded and the RADIUS server sent an Access-Accept. However, the workstation cannot ping the default gateway, pointing to a connectivity issue after authentication. The most likely cause is that the RADIUS server returned a VLAN assignment (via the Tunnel-Private-Group-ID attribute) that placed the port in a VLAN that is not the intended one, such as a management VLAN without a gateway, or a VLAN missing a routed SVI, leaving the workstation isolated despite successful authentication.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
The RADIUS server has not been configured with the correct shared secret, causing authentication to fail silently.
Why it's wrong here
The show authentication sessions output shows 'Authz Success', meaning authentication and authorization succeeded. A shared secret mismatch would cause authentication failure, not a successful authorization.
✓
The RADIUS server returned a VLAN ID that placed the port in a VLAN lacking connectivity to the default gateway, such as a VLAN without an SVI or incorrect subnet assignment.
Why this is correct
After successful 802.1X authentication, the switch can dynamically assign the port to a VLAN specified in the RADIUS Access-Accept message. If that VLAN exists but is not the correct user VLAN—for example, a dead-end VLAN or a VLAN where the default gateway IP is not configured or reachable—the device will appear authorized but will be unable to reach the gateway, exactly matching the symptoms.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The switch port is in 'err-disabled' state due to a port-security violation, preventing any traffic.
Why it's wrong here
The show command output clearly shows the port status as 'AUTHORIZED' and 'Authz Success'. There is no indication of err-disable. Port-security violations would show a different status.
✗
The workstation's supplicant is not configured with the correct EAP method, causing the authentication to use the guest VLAN instead.
Why it's wrong here
The output shows 'authVlan = 100' and the session is authorized with 'method = dot1x' and 'status = AUTHORIZED'. This indicates the supplicant successfully authenticated and was placed in the auth VLAN, not the guest VLAN.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓The RADIUS server returned a VLAN ID that placed the port in a VLAN lacking connectivity to the default gateway, such as a VLAN without an SVI or incorrect subnet assignment.Correct answer▾
Why this is correct
After successful 802.1X authentication, the switch can dynamically assign the port to a VLAN specified in the RADIUS Access-Accept message. If that VLAN exists but is not the correct user VLAN—for example, a dead-end VLAN or a VLAN where the default gateway IP is not configured or reachable—the device will appear authorized but will be unable to reach the gateway, exactly matching the symptoms.
✗The RADIUS server has not been configured with the correct shared secret, causing authentication to fail silently.Wrong answer — click to see why▾
Why this is wrong here
The show authentication sessions output indicates 'Authz Success', meaning authentication and authorization succeeded. A shared secret mismatch would cause authentication failure, not a successful authorization.
Why candidates choose this
Students often confuse shared secret issues with other RADIUS configuration problems, but the authentication success message rules this out.
✗The switch port is in 'err-disabled' state due to a port-security violation, preventing any traffic.Wrong answer — click to see why▾
Why this is wrong here
The show command output clearly shows the port status as 'AUTHORIZED' and 'Authz Success'. There is no indication of err-disable. Port-security violations would show a different status, such as 'err-disabled' or 'security-violation'.
Why candidates choose this
Port security violations are a common cause of connectivity issues, and students may assume any access problem is due to err-disable without checking the port status.
✗The workstation's supplicant is not configured with the correct EAP method, causing the authentication to use the guest VLAN instead.Wrong answer — click to see why▾
Why this is wrong here
The output shows 'authVlan = 100' and the session is authorized with 'method = dot1x' and 'status = AUTHORIZED'. This indicates the supplicant successfully authenticated and was placed in the auth VLAN, not the guest VLAN. If the supplicant had failed, the port would be in the guest VLAN.
Why candidates choose this
Students may think that EAP method mismatch leads to guest VLAN usage, but the authorization success shows the supplicant authenticated correctly.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between authentication success (port state 'authorized') and network connectivity success (correct VLAN assignment), tricking candidates into focusing on authentication failures when the real issue is a post-authentication VLAN misconfiguration.
Trap categories for this question
Command / output trap
The show authentication sessions output shows 'Authz Success', meaning authentication and authorization succeeded. A shared secret mismatch would cause authentication failure, not a successful authorization.
Detailed technical explanation
How to think about this question
In 802.1X with VLAN assignment, the RADIUS server sends a successful Access-Accept packet that includes the Tunnel-Type (VLAN), Tunnel-Medium-Type (802), and Tunnel-Private-Group-ID (VLAN ID) attributes (RFC 3580). The switch dynamically places the port into the specified VLAN, overriding any static VLAN configuration. If the VLAN ID is invalid (e.g., 0, 4095, or a VLAN not created on the switch), the port may remain in the 'authorized' state but with no functional VLAN, effectively isolating the host. This is a common misconfiguration when the RADIUS server is not synchronized with the switch's VLAN database.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
Network Services and Security — This question tests Network Services and Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The RADIUS server returned a VLAN ID that placed the port in a VLAN lacking connectivity to the default gateway, such as a VLAN without an SVI or incorrect subnet assignment. — The switch port is in the 'authorized' state, indicating that 802.1X authentication succeeded and the RADIUS server sent an Access-Accept. However, the workstation cannot ping the default gateway, pointing to a connectivity issue after authentication. The most likely cause is that the RADIUS server returned a VLAN assignment (via the Tunnel-Private-Group-ID attribute) that placed the port in a VLAN that is not the intended one, such as a management VLAN without a gateway, or a VLAN missing a routed SVI, leaving the workstation isolated despite successful authentication.
What should I do if I get this 200-301 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A network administrator has configured 802.1X port-based authentication on a Cisco IOS-XE switch port connected to a single PC. The port is in the 'authorized' state, but the PC cannot reach any network resources beyond its directly connected switch. The switch is configured to use RADIUS for authentication. What is the most likely cause of this issue?
hard
A.The switchport is in access mode and not trunking, so the PC cannot reach other VLANs.
✓ B.The RADIUS server is not returning a VLAN assignment, so the port remains in the default VLAN, but the PC needs to be in a different VLAN to reach resources.
C.The switch is not configured with 'aaa new-model' and therefore AAA is not enabled.
D.The PC is not configured for 802.1X supplicant, so it cannot authenticate properly.
Why B: The RADIUS server can return a VLAN assignment as part of the Access-Accept message (via RADIUS attribute 64 or 81). If the server does not send a VLAN, the port remains in the configured access VLAN (often VLAN 1). If the PC needs to be in a different VLAN to reach network resources, it will be isolated even though 802.1X authentication succeeded and the port is authorized.
Last reviewed: Jun 11, 2026
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.