The answer is that the certificate uses the SHA-1 hash algorithm, which is the primary security concern. SHA-1 is cryptographically weak because it is susceptible to collision attacks, where two different inputs produce the same hash, allowing an attacker to forge a valid certificate. This deprecation is enforced by major browsers and industry standards, making any SHA-1 signed certificate untrustworthy for TLS. On the CompTIA SecurityX CAS-004 exam, this tests your ability to identify deprecated cryptographic algorithms in certificate analysis, often presented alongside distractors like self-signed status or key length. A common trap is confusing SHA-1 with the acceptable SHA-256 or mistaking a 2048-bit RSA key—which is still secure—for the vulnerability. Remember the mnemonic: SHA-1 is a “one-way ticket to deprecation,” so if you see it, flag it immediately.
CAS-004 Security Engineering Practice Question
This CAS-004 practice question tests your understanding of security engineering. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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
Certificate:
Data:
Version: 3 (0x2)
Serial Number: 0x1234567890abcdef
Signature Algorithm: sha1WithRSAEncryption
Issuer: C=US, O=Example Corp, CN=Example Root CA
Validity
Not Before: Jan 1 00:00:00 2024 GMT
Not After : Dec 31 23:59:59 2024 GMT
Subject: C=US, O=Example Corp, CN=server01.example.com
Subject Public Key Info:
Public Key Algorithm: rsaEncryption
RSA Public-Key: (2048 bit)
Modulus: ...
X509v3 extensions:
...
Refer to the exhibit. A security engineer is reviewing an X.509 certificate used for TLS. Which security concern should the engineer identify?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The certificate uses the SHA-1 hash algorithm
The certificate uses SHA-1 as the signature algorithm, which is cryptographically weak and deprecated by major browsers and industry standards. Self-signed would show issuer == subject, key length 2048 is acceptable, and one-year validity is normal.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 certificate uses the SHA-1 hash algorithm
Why this is correct
SHA-1 is considered broken and should not be used for digital signatures.
Related concept
Static NAT maps one inside address to one outside address.
✗
The RSA key length is 2048 bits
Why it's wrong here
2048-bit RSA is currently acceptable and meets security standards.
✗
The certificate is self-signed
Why it's wrong here
The issuer and subject are different (Example Root CA vs server01), so it is not self-signed.
✗
The validity period is only one year
Why it's wrong here
One-year validity is common for TLS certificates and is not a security concern.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CAS-004 NAT questions on configuration and troubleshooting.
Security Engineering — This question tests Security Engineering — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The certificate uses the SHA-1 hash algorithm — The certificate uses SHA-1 as the signature algorithm, which is cryptographically weak and deprecated by major browsers and industry standards. Self-signed would show issuer == subject, key length 2048 is acceptable, and one-year validity is normal.
What should I do if I get this CAS-004 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CAS-004 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Question Discussion
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