Network and Security (Foundations (D315))

Correct Answer:

Network

Explanation:

IP addresses operate at the Network layer of the OSI model. This layer is responsible for logical addressing, routing, and delivering packets from the source device to the destination across multiple networks. The Internet Protocol (IP) is the primary protocol used here, enabling devices to be uniquely identified and ensuring that data reaches the correct location.

Correct Answer B. It authenticates only the server to the user

Explanation:

A single-sided certificate, also known as a server certificate, is primarily used in protocols like HTTPS to authenticate the identity of a server to the client. This ensures that the user is communicating with a legitimate server rather than an imposter. However, it does not authenticate the user to the server, as client authentication requires mutual authentication with both parties presenting certificates.

Why other options are wrong:

A. It authenticates both the server and the user is incorrect because single-sided certificates only verify the server’s identity. To authenticate both the server and the user, mutual authentication using client certificates is required.

C. It encrypts data without authentication is incorrect because while encryption can be used alongside certificates, authentication is the primary function of a single-sided certificate. Encryption mechanisms like TLS rely on certificates, but authentication is the key role of a single-sided certificate.

D. It requires mutual authentication between parties is incorrect because mutual authentication requires both the client and server to present valid certificates. A single-sided certificate only verifies the server’s identity, not the client’s.

Correct Answer B. Access associated with the classification of data.

Explanation

Mandatory Access Control (MAC) is a security model where access permissions are strictly defined by a centralized authority based on the classification of data. Users are granted access based on their security clearance, and they can only access data if their clearance level matches or exceeds the classification of the data. This model is commonly used in environments requiring high security, such as government and military systems, to prevent unauthorized access and enforce strict data control.

Why other options are wrong

A. Access rights indicated by the role of the individual

This is incorrect because role-based access control (RBAC), not MAC, assigns permissions based on an individual's role within an organization. In MAC, access is dictated by data classification and security labels rather than user roles.

C. A system administrator to centralize policy.

This is incorrect because, while administrators enforce MAC policies, the access control itself is dictated by predefined classification levels and security policies. Administrators do not arbitrarily assign access but instead follow strict classification rules.

D. Rights to be assigned by the data owner.

This is incorrect because discretionary access control (DAC), not MAC, allows data owners to determine access permissions. In MAC, access rights are determined by system-enforced policies and classification levels, removing discretion from individual users.

Correct Answer B. To request a digital certificate from a Certificate Authority (CA)

Explanation:

A Certificate Signing Request (CSR) is a message sent to a Certificate Authority (CA) to apply for a digital certificate. The CSR contains the public key and information about the requester (such as domain name, organization, and location). The CA uses this request to validate the applicant's identity and issue a corresponding digital certificate, which is used for secure communications in Public Key Infrastructure (PKI).

Why other options are wrong:

A. To generate a public key for encryption purposes

A CSR does not generate a public key; rather, the key pair (public and private key) is created before generating the CSR. The CSR includes the public key, which is sent to the CA for certificate issuance.

C. To store private keys securely

A CSR does not store private keys. Private keys are generated and stored securely on the requester's system, while only the public key is included in the CSR and sent to the CA.

D. To verify the identity of a user

While a CSR includes identity information, it is not responsible for verifying the user's identity. Instead, the CA verifies the provided information before issuing a certificate.

Correct Answer D. All of the above

Explanation:

Replay attacks occur when an attacker intercepts and replays legitimate data transmissions to trick the system into accepting duplicate or unauthorized requests. To counter this, several methods can be used. Time stamps help prevent replay attacks by making sure packets are processed within a valid time window, rejecting old or duplicated packets. Sequence numbers ensure that packets are received in the correct order and detect duplicated ones, reducing the effectiveness of replay attacks. Challenge-response protocols involve sending a unique challenge that must be correctly answered using a cryptographic key, ensuring the response cannot be reused by an attacker. Combining these methods strengthens network security against replay attacks.

Why other options are wrong:

A. Time stamps in the packet alone is insufficient because time synchronization issues can arise, leading to potential vulnerabilities or rejected legitimate packets. While time stamps help, they work best when combined with other measures.

B. Sequence numbers in the packet alone is not a complete solution since attackers could potentially predict or manipulate sequence numbers. If sequence numbers are implemented without encryption or other security features, they may not fully prevent replay attacks.

C. Challenge response protocols alone help in preventing replay attacks, but they do not address all scenarios, such as delayed but still valid responses. When used in combination with time stamps and sequence numbers, security is significantly improved.

Correct Answer D. To prevent unauthorized access

Explanation

Data encryption is a security mechanism used to protect sensitive information by converting it into an unreadable format. Only authorized users with the correct decryption key can access the data. This helps to prevent unauthorized access, data breaches, and cyber threats, ensuring confidentiality and integrity.

Why other options are wrong

A. To reduce data storage costs.

This is incorrect because encryption does not reduce storage costs. In some cases, encrypted data may even require more storage due to the additional processing and security measures applied.

B. To simplify data transmission.

This is incorrect because encryption does not simplify data transmission. While it ensures secure transmission, it actually adds computational overhead for encryption and decryption processes.

C. To increase data accessibility.

This is incorrect because encryption restricts access to only authorized users. Instead of increasing accessibility, it ensures that only the intended recipients can decrypt and read the data.

Correct Answer:

Integrity

Explanation:

Hashing user passwords before storage ensures that they cannot be modified or tampered with without detection. This directly supports the principle of integrity, which is concerned with maintaining the accuracy, consistency, and trustworthiness of data. By hashing, the system protects against unauthorized alterations, ensuring stored passwords remain unchanged and valid.

Correct Answer A. A role is an identity that is used to grant a temporary set of permissions to make AWS service requests.

Explanation

An AWS IAM role is a temporary identity used to grant permissions for accessing AWS services. Unlike IAM users, roles do not have long-term credentials; instead, they use temporary security credentials generated by AWS Security Token Service (STS). Roles are useful for granting permissions to applications, services, or users without requiring static credentials, enhancing security and flexibility in cloud environments.

Why other options are wrong

B. A role is an identity that is used to grant a permanent set of permissions to make AWS service requests.

This is incorrect because IAM roles provide temporary credentials, not permanent ones. Users or services assume roles when needed, and the permissions expire after a defined duration, reducing security risks.

C. A role is a document that defines which resources a user can access.

This is incorrect because an IAM policy, not a role, defines which resources a user can access. Roles use policies to determine permissions, but they themselves are not documents.

D. A role is a person or application that can authenticate with an AWS account.

This is incorrect because an IAM role itself does not authenticate directly. Instead, entities (such as users or AWS services) assume roles to gain permissions. Authentication is handled separately through AWS IAM users, federated identities, or service accounts.

Correct Answer C. Wildcard certificate

Explanation

A wildcard certificate is used to secure multiple subdomains under a single domain name. For example, a wildcard certificate for *.example.com can be used for www.example.com, mail.example.com, and blog.example.com. This is particularly useful for organizations managing multiple services under one domain, reducing the need for multiple certificates.

Why other options are wrong

A. Root certificate

A root certificate is the foundational certificate issued by a Certificate Authority (CA). It is used to sign other certificates in a Public Key Infrastructure (PKI) and does not serve the function of securing multiple subdomains.

B. Self-signed certificate

A self-signed certificate is issued by an entity for itself rather than by a trusted CA. While it can be used for internal testing, it is not recognized as valid by most browsers and does not inherently support multiple subdomains.

D. S/MIME certificate

An S/MIME (Secure/Multipurpose Internet Mail Extensions) certificate is used to encrypt and sign emails to ensure secure communication. It is unrelated to securing subdomains.

E. Code signing certificate

A code signing certificate is used to verify the authenticity and integrity of software applications. It ensures that the software has not been tampered with, but it does not provide security for web domains or subdomains.