SK0-005 server-administration Practice Question
Exhibit
Log Name: System Source: Microsoft-Windows-Kerberos-Key-Distribution-Center Event ID: 27 Level: Error Description: While processing a TGS request for the target server HTTP/webserver.contoso.com, the account webserver$ did not have a suitable key for generating a Kerberos ticket (the missing key has an ID of 8). The requested etypes : 18 17 3 1. The accounts available etypes : 23 -133 -128 3 1.
Refer to the exhibit. A server administrator encounters an authentication issue when accessing a web server. The exhibit shows an error from the Domain Controller's event log. What is the most likely cause of the problem?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The web server's service account is not configured to support AES encryption types.
Option B is correct because the error shows that the requested encryption types (etype 18 is AES) are missing from the account's available etypes, indicating the service account is not configured to support AES. Option A would produce a clock skew error. Option C would result in a password expiration event. Option D would cause name resolution or host not found errors, not a Kerberos encryption mismatch.
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 web server's service account is not configured to support AES encryption types.
Why this is correct
The missing key and the mismatch between requested (AES etype 18) and available etypes directly point to missing AES support on the account.
- ✗
The DNS service is not resolving the web server's FQDN.
Why it's wrong here
DNS issues would prevent the client from contacting the server at all, not generate a Kerberos ticket encryption error.
- ✗
The domain controller clock is out of sync with the web server.
Why it's wrong here
Clock skew generates a different error (KDC_ERR_SKEW) and is not indicated by an encryption type mismatch.
- ✗
The service account for the web server has an expired password.
Why it's wrong here
Password expiration would cause an authentication failure with event ID 4771, not an encryption type error.
Quick reference
Symmetric Encryption Algorithm Comparison
| Algorithm | Key Size | Block Size | Status | Notes |
|---|---|---|---|---|
| AES-128 | 128-bit | 128-bit | Current standard | NIST approved; WPA3, TLS |
| AES-256 | 256-bit | 128-bit | Current standard | Preferred for sensitive / govt data |
| 3DES | 112-bit effective | 64-bit | Deprecated (2023) | Replaced by AES |
| DES | 56-bit | 64-bit | Broken | Cracked in < 24 h; never deploy |
| ChaCha20 | 256-bit | Stream cipher | Current | TLS 1.3, WireGuard |
Go deeper
Related to this question
Learn chapter
Authentication, Authorization, and Encryption
Key term
Service account
A service account is a special type of account used by an application or a virtual machine, rather than a human user, to authenticate and interact with cloud services and APIs securely.
Key term
Service
A service is a software component or system that performs a specific function and is available to be used by other programs or users over a network.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed July 2026 · checked against the official CompTIA exam blueprint
This SK0-005 practice question is part of Courseiva's free CompTIA 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 SK0-005 exam.