CNX-001 practice question 7 of 15

A user reports an issue connecting to a database server. The front-end application for this database is hosted on the company's web server. The…

Full set: 84 questions

A user reports an issue connecting to a database server. The front-end application for this database is hosted on the company's web server. The network engineer has changed the network subnet that the company servers are located on along with the IP addresses of the servers. These are the new

configurations:

  • New subnet for the servers is 10.10.10.64/27
  • Web server IP address is 10.10.10.101
  • Database server IP is 10.10.10.93

Which of the following is most likely causing the user's issue?

Answer options
A: The web application server is not forwarding the requests.
B: The database server firewall is blocking the port to the database.
C: The DNS server is not resolving properly.
D: The web server does not have the correct network configuration. Correct answer
Correct Answer:
D. The web server does not have the correct network configuration.
Explanation

The new server subnet is 10.10.10.64/27. A /27 CIDR notation corresponds to a subnet mask of 255.255.255.224. This configuration creates subnets with 32 total addresses. For the 10.10.10.64 network, the network address is 10.10.10.64 and the broadcast address is 10.10.10.95. Therefore, the valid range for assignable host IP addresses is 10.10.10.65 to 10.10.10.94. The database server's IP (10.10.10.93) is valid. However, the web server's IP (10.10.10.101) is outside this valid range. This incorrect IP configuration for the web server is the most likely cause of the connectivity issue.

Why Incorrect

A. The web application server is not forwarding the requests. This is a symptom of the problem, not the root cause. The server cannot forward requests if its fundamental network configuration is invalid for the assigned subnet.
B. The database server firewall is blocking the port to the database. While a possible issue in general, the provided information points directly to a definitive IP addressing error, making it the most probable cause.
C. The DNS server is not resolving properly. The problem stems from a fundamental Layer 3 misconfiguration. Even if DNS were resolving correctly, the web server's IP address is invalid for its subnet, preventing communication.

References

1. Rekhter

Y.

Li

T.

& Hares

S. (2006). Classless Inter-Domain Routing (CIDR): The Internet Address Assignment and Aggregation Plan. RFC 4632. Internet Engineering Task Force (IETF). Section 3.1 describes the concept of a network prefix (/27) defining the range of addresses within a block.

2. MIT OpenCourseWare. (2011). 6.02 Introduction to EECS II: Digital Communication Systems

Fall 2011. Lecture 17: Network Layer: IP. The lecture materials explain how an IP address and its subnet mask determine network membership

which is the core principle violated by the web server's configuration.

3. Dordal

P. L. (2019). An Introduction to Computer Networks. Loyola University Chicago

Department of Computer Science. Chapter 9.3

"Subnets

" provides detailed examples of calculating subnet ranges

network addresses

and broadcast addresses

confirming that 10.10.10.101 is outside the 10.10.10.64/27 range.

Scroll to Top