F5-CTS-LTM BIG-IP Local Traffic Manager Practice Question
Exhibit
ltm monitor https /Common/app_monitor {
defaults-from /Common/https
send "GET /health.php HTTP/1.1\r\nHost: example.com\r\nConnection: Close\r\n\r\n"
}Refer to the exhibit. The LTM Specialist discovers that the HTTPS monitor is failing. The server logs indicate that the requests are reaching the web server, but the server is returning a 400 Bad Request error. What is the most likely cause?
⚠ Common exam trap
Candidates often assume the 400 Bad Request error is caused by a broken network link or general server downtime, missing that the custom HTTP send string explicitly requires a matching Host header.
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 Host header in the send string does not match the server's expected virtual host.
The exhibit shows a manually defined send string that includes a Host header. A 400 Bad Request often indicates that the server does not recognize the Host header or the HTTP version specified in the request. In this configuration, the 'Host: example.com' header might be mismatched with the server's virtual host configuration, causing it to reject the request, which prevents the monitor from correctly identifying the server as healthy.
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 BIG-IP is using the wrong SSL profile for the monitor.
Why it's wrong here
While an SSL profile mismatch could prevent a connection entirely, the fact that the server responds with a 400 error implies the SSL handshake was successful. A 400 error is an application-layer response, meaning the server received the request but rejected the specific format of it.
- ✓
The Host header in the send string does not match the server's expected virtual host.
Why this is correct
When using HTTP/1.1, the Host header is mandatory. If the server expects a specific host header value but receives 'example.com', it will reject the request with a 400 status. The monitor must be updated to match the hostname configured on the backend web server.
- ✗
The monitor is missing a 'Receive String' definition.
Why it's wrong here
While it is best practice to include a receive string, the absence of one defaults the monitor to look for any successful HTTP response. A 400 error is a valid HTTP response code, but it is not a 'success' code that would cause the monitor to pass.
- ✗
The monitor is using the wrong HTTP method.
Why it's wrong here
The monitor uses the GET method, which is standard for health checks. Unless the application specifically requires POST or HEAD methods, the GET request is sufficient. The error 400 points specifically to a request formatting issue, not an incorrect HTTP method selection.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official F5 exam blueprint
This F5-CTS-LTM practice question is part of Courseiva's free F5 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 F5-CTS-LTM exam.