All N10-009 Test Inside CompTIA Questions

To redirect a network resource that has moved from a local network to a Software-as-a-Service (SaaS) solution, the network administrator needs to configure a DNS record that maps an alias to the new canonical name (hostname) of the SaaS provider’s server. The CNAME (Canonical Name) record is used to alias one domain name to another, effectively redirecting requests to the new hostname without needing to update the IP address directly. This is ideal for SaaS solutions, where the provider’s server hostname is used, and the IP address may change dynamically.

Why not TXT? A TXT record is used to store arbitrary text data, such as SPF records for email authentication or verification strings, not for redirecting resources.

Why not AAA? There is no such thing as an "AAA" record in DNS. This might be a typo for AAAA (IPv6 address record), but AAAA maps a hostname to an IPv6 address, not an alias.

Why not PTR? A PTR record is used for reverse DNS lookups (mapping an IP address to a hostname), not for redirecting a resource to a new hostname.

Role of the Hosts File:

The hosts file is a local file on a computer that maps hostnames to IP addresses. It can be used to override DNS resolution by providing a static mapping of a hostname to an IP address.

Common Issues with the Hosts File:

If an incorrect IP address is mapped to a hostname in the hosts file, it can cause the computer to resolve the hostname to the wrong IP address. This can lead to navigation issues for specific websites while other users, relying on DNS, do not face the same problem.

Why Other Options are Less Likely:

Self-signed certificate: Relates to SSL/TLS and would cause a security warning, not a navigation failure.

Nameserver record: Affects all users, not just one.

IP helper: Used to forward DHCP requests and is unrelated to DNS resolution issues.

Troubleshooting Steps:

Check the hosts file on the affected user's computer (C:\Windows\System32\drivers\etc\hosts on Windows or /etc/hosts on Unix/Linux).

Look for entries that map the problematic hostname to an incorrect IP address and correct or remove them.

A /21 subnet mask means 21 bits are network bits:

8 + 8 + 5 = 21 → leaves 11 bits for hosts.

Subnet mask in binary: 11111111.11111111.11111000.00000000

Converted to decimal: 255.255.248.0

Therefore:

A. /19 = 255.255.224.0

B. /20 = 255.255.240.0

✅ C. /21 = 255.255.248.0 ← correct

D. /22 = 255.255.252.0

Answer correction: The correct option is C. 255.255.248.0, not B.

References (CompTIA Network+ N10-009):

Domain: Networking Concepts — Subnetting, CIDR notation, dotted decimal masks.

An incorrect pinout on the patch cable could prevent network connectivity due to mismatched wiring. Even if the cables are the correct length and type, a pinout issue can cause continuity problems and prevent data transmission. Proper crimping with the correct pinout is essential for network cables to function. (Reference: CompTIA Network+ Study Guide, Chapter on Network Media and Topologies)