Network+ (N10-009) DNS Records Practice Flashcards

Flashcards covering essential DNS record types for the CompTIA Network+ (N10-009) exam, including definitions and high-yield exam tips.

A Record (Address Record)

Maps a hostname to an IPv4 address. Exam Tip: 'A' stands for Address. If the question specifies IPv4, the answer is always a single A record.

AAAA Record (Quad-A Record)

Maps a hostname to an IPv6 address. Exam Tip: IPv6 addresses are $128$-bit, which is four times larger than a $32$-bit IPv4 address.

CNAME Record (Canonical Name)

An alias that maps one domain name to another domain name (not to an IP address). Think of it as a 'nickname' for routing multiple names to the same single host without changing IP configurations.

MX Record (Mail Exchanger)

Redirects email traffic to the correct incoming mail servers for a domain using a preference/priority number (e.g., $10, 20, 30$). Mail servers attempt the lowest preference number first; backup servers are set with higher numbers.

PTR Record (Pointer Record)

Resolves an IP address to a hostname for Reverse DNS Lookups, the exact opposite of an A/AAAA record. Found in 'Reverse Lookup Zones', they are frequently used by email servers to verify sending server identity and prevent spam.

TXT Record (Text Record)

Allows administrators to insert arbitrary text into DNS records to verify domain ownership and secure email. Key frameworks using this include SPF (authorized IPs), DKIM (cryptographic signatures), and DMARC (failure policies) to combat email spoofing and phishing.

SRV Record (Service Locator)

Specifies the hostname and port number for specific services, such as VoIP, SIP, or Windows Active Directory domain controllers. Use this when a client needs to locate a specific service or port via DNS.

NS Record (Name Server)

Identifies the authoritative DNS servers for a specific zone. It tells the internet where to go to query the actual records (A, MX, etc.) for that domain.

SOA Record (Start of Authority)

The very first record in any DNS zone file containing vital administrative data, including the primary name server, administrator's email, and the serial number. The serial number increments with changes and is key for monitoring DNS synchronization and zone transfers.