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Practice choosing DNS records

Ten common record types, with definitions and practical scenarios. Choose a focused set or practice all ten.

Optional. Leave blank for the default challenge; enter up to 128 characters to repeat a particular round.

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Answer recorded. Corrections appear at the end of the round.

Review what to practice next

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Curated bank v1.0.0: 20 original prompts across 10 common DNS types. Sources verified 11 September 2026 against the IANA registry revision of 28 August 2026 and the linked RFCs. This is independent practice, not an exhaustive registry test or certification exam.

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Record-function performance

Which record functions need more practice? Counts reflect only this round, not overall proficiency.

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Answer ledger

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DNS Record Lookup Look up DNS records for a domain, URL or IP through Google or Cloudflare with response codes, returned TTL evidence and DNSSEC flags.
DNS Record Enumerator Enumerate public DNS records for a domain or IP through Cloudflare or Google, compare query coverage, and flag mail or DNSSEC gaps.
DNS Configuration Report Audit a domain's public DNS for authority, address and mail-policy gaps while comparing TTL horizons and resolver-visible evidence across common records.
DNS Zone File Generator Draft a BIND or provider-ready DNS zone file with normalized records, SOA and TTL checks, plus mail and DNSSEC review warnings.

A website can resolve correctly while email for the same domain goes to the wrong server. The Domain Name System (DNS) publishes several kinds of information, not one universal destination for a domain. Address records help locate hosts, mail records identify mail exchangers, and other records describe aliases, name servers or policies. Choosing the right record type means identifying which job the information needs to do.

Every DNS record belongs to a particular name, called its owner. A record at example.com and one at www.example.com belong to different names, even though they share a domain. The type tells a reader how to interpret the value. An address, a server name and a policy string are not interchangeable simply because a DNS management form accepts text for all three.

Forward address lookup
Starts with a host name and asks for its address. A records hold Internet Protocol version 4 (IPv4) addresses, while AAAA records hold Internet Protocol version 6 (IPv6) addresses.
Alias
Uses CNAME to make one name refer to another name. The target is a domain name rather than an address, and an address lookup may continue at that target.
Reverse lookup
Starts with an address represented in the reverse DNS namespace and commonly uses PTR to obtain a host name. Its records are maintained separately from forward address records.

A hosting provider that supplies an IP address and one that supplies a target host name are therefore asking for different kinds of DNS data. An alias can avoid copying a target's address into several records, but it also depends on the target continuing to resolve. A CNAME is not a web redirect. It does not change a browser's URL path or configure the destination website to accept the original name.

DNS also separates responsibility for publishing records from the work of finding them. An authoritative name server serves the records for a zone, an administratively managed portion of the DNS name tree. A recursive resolver finds answers on behalf of clients and may keep copies in a cache. Delegation identifies the servers responsible for a child zone; it is not the same operation as assigning an address to a website.

The time to live (TTL) describes how long a cached record may normally be reused before it needs refreshing. Shorter TTLs reduce ordinary cache retention but increase lookup work. A DNS change is not a simultaneous update of every client's cached answer, and TTL is not a guarantee that a new value will be visible everywhere at a particular moment.

Recognizing a record's purpose helps distinguish address, mail, delegation and policy problems. It does not establish that a live configuration is correct. The owner name, value, authoritative zone and consuming application must also agree. A correctly chosen record type with the wrong target can still send traffic or mail to the wrong place.

How to Use This Tool:

Choose definitions to identify records from their descriptions, or scenarios to choose records for an operational task. The default is Common records · scenarios, five questions and feedback After each answer.

  1. Choose a Practice set. Common records covers all ten types. Addresses and names focuses on A, AAAA, CNAME and PTR, while Zones and services covers NS, SOA, MX, TXT, SRV and CAA. Each focus has separate definitions and scenarios sets. Other record types may still appear as incorrect choices.
  2. Select the Question count. Common-record sets offer 2, 5 or 10 questions; address-and-name sets offer 2 or 4; zone-and-service sets offer 2, 5 or 6. The largest count covers every prompt in that set once. Shorter rounds need not include every record function.
  3. Choose Feedback. After each answer reveals correctness, an explanation and a source after your selection. At the end records each choice without showing correctness until the completed-round review.
  4. Set an optional Replay seed under Advanced, then select Start practice. A blank seed uses a fixed default challenge, not a newly randomized round. Keep the seed, setup and quiz version unchanged to reproduce a round.
    The replay seed accepts up to 128 characters, with surrounding spaces ignored. If its length warning appears, shorten it. Until corrected, the default seed is used instead.
  5. Select one of the four answers. Your selection is saved immediately and cannot be changed within that attempt. Read the feedback when enabled, then select Next question. After the last answer, select View results. There is no skipped-question or early-finish result.
  6. Review the corrections before replaying. After a round with mistakes, Retry missed starts another attempt containing only wrong answers, while Replay same seed repeats the questions and option order with answers cleared. Try a new seed uses a different seed but can repeat prompts. Change setup returns to the setup choices and clears the current attempt.

Interpreting Results:

During a round, Practice status and the progress percentage describe how many questions you have answered, not how many are correct. The final summary gives correct answers out of the round's question count. Missed answer review explains the mistakes, and the Answer ledger retains every question with your choice, the correct choice, its outcome, explanation and source.

Record-function performance groups A and AAAA under Addressing, CNAME and PTR under Names, NS and SOA under Zone control, MX and SRV under Services, and TXT and CAA under Policy. Its bars count Correct and Missed answers from this round only. An untested function has not been assessed, and a longer correct-answer bar may simply reflect more questions. Review focus uses the category with the most misses, not a standardized proficiency rating.

A Perfect round means no selected question was missed. It does not establish mastery, and repeating an identical round can reflect recognition of familiar questions. There is no official pass mark or proficiency band. Use the explanations to identify the record distinction you misunderstood, then try the corresponding scenarios or definitions. A one-question retry is useful correction practice, not a score directly comparable with a full round.

Bank version 1.0.0 contains 20 original prompts, one definition and one scenario for each of ten common types. Its recorded source-check date is 11 September 2026, using the Internet Assigned Numbers Authority (IANA) registry revision dated 28 August 2026 and the cited standards. These are independent practice questions, not official exam questions, exhaustive registry coverage or certification. The quiz does not query or configure your DNS, validate a zone, or establish professional competence. Actual DNS queries are a separate follow-on activity; the guides in References explain how to make them with dig or Windows tools.

Technical Details:

A DNS resource record associates data with an owner name. Its record type determines the meaning and structure of that data. Several types contain another domain name, but an alias target, authoritative server, mail exchanger and reverse-lookup result have different roles.

Record types and their data

Type Data carried Distinguishing rule
A One 32-bit IPv4 address. An address record, not a domain-name alias.
AAAA One 128-bit IPv6 address. Publishing A does not automatically publish AAAA, or vice versa.
CNAME The canonical target name for an alias. The owner is the alias; the value is another domain name.
PTR A domain-name pointer. Commonly supplies the host-name result of a reverse lookup.
NS An authoritative name server's domain name. Identifies a server; its address records and any required delegation glue are separate.
SOA Start of Authority data: primary server, responsible mailbox, serial, refresh, retry, expire and minimum fields. Describes zone administration rather than a website or mail destination.
MX A preference number and mail-exchanger domain name. Lower preference numbers are preferred. The record does not contain an address or arbitrary service port.
TXT One or more character strings. The consuming protocol determines their meaning, including Sender Policy Framework (SPF) policies.
SRV Priority, weight, port and a service target name. Lower priority numbers are preferred; weight influences selection among equal-priority targets.
CAA Certification Authority Authorization properties expressed as flags, a tag and a value. Controls certificate issuance authorization. It does not hold the certificate or its private key.

Reading names, addresses and aliases

Zone-file notation separates the owner, TTL, class, type and record data. These illustrative entries show an alias, its target address and an independently maintained reverse record. The forward and reverse entries belong in their respective zones; together they are not a complete zone configuration.

www.example.com.              3600 IN CNAME web.example.com.
web.example.com.              3600 IN A     192.0.2.10
10.2.0.192.in-addr.arpa.        3600 IN PTR   web.example.com.

The first field is the owner name, followed by a TTL of 3,600 seconds and the Internet class, IN. The type determines how to read the remaining record data, often called RDATA. Trailing dots make the domain names absolute rather than relative to a zone's origin.

An address lookup for www.example.com follows the CNAME to web.example.com, whose A record supplies the IPv4 address. The reverse owner is formed by reversing the address's four decimal octets and adding in-addr.arpa. IPv6 reverse names instead reverse the individual hexadecimal digits of the fully expanded address under ip6.arpa. Creating or changing a forward record does not automatically create or update its PTR counterpart.

An ordinary CNAME owner cannot also hold records such as A, AAAA, MX, TXT, NS or SOA. That prevents an ordinary CNAME at a zone apex, where the zone's SOA and NS records must exist. Separately, MX and NS target names must have address records rather than being CNAME aliases. SRV service targets have the same no-alias requirement.

Delegation and zone timing

NS identifies authoritative servers, while SOA describes zone management. The SOA serial identifies a zone version so secondary servers can detect updates. Refresh and retry describe when to check again, and expire limits how long an unrefreshed secondary copy remains authoritative. These timers use seconds; they are not the caching TTL of every host record.

Delegation glue supplies address records when resolving a delegated server's own name would otherwise depend on reaching that same server. For example, delegating lab.example.com to ns1.lab.example.com needs an address that can be obtained from the parent delegation. Glue is address data, not another name for an NS record.

The SOA minimum field has a separate modern role in negative caching, where a resolver remembers that a name or requested record type was absent. Its value and the SOA record's TTL determine the initial negative-cache lifetime by taking the smaller value. It is not a universal minimum TTL imposed on every record in the zone.

Mail, service discovery and policy

MX preference ranks mail exchangers for the same owner name. Preference 10 is preferred to 20; neither number is a network port. SRV adds a port and a weight, with an owner commonly written in the form _service._proto.name. For SRV, priority is considered before weight. A higher weight does not override a worse priority, and it is not a guaranteed traffic percentage. Clients must support the relevant service-discovery convention to use these records.

SPF distinguishes sender authorization from mail routing. An SPF policy beginning v=spf1 is published in TXT, not the discontinued dedicated SPF record type. MX records alone do not declare that policy. One TXT record may contain several strings, each limited to 255 octets; SPF joins those strings without inserting spaces. That is different from publishing multiple separate SPF policies at the same owner name, which is not allowed.

CAA uses properties such as issue and issuewild to express issuance authorization. An issuewild property applies to wildcard certificates and takes precedence over issue for a wildcard request when present. It is ignored for a non-wildcard request. CAA authorization does not replace the certificate authority's other validation requirements.

Practice score and progress

Each question awards one point for the correct record type and zero for another offered answer. All questions have equal weight, with no partial credit or guessing penalty. Let C be correct answers, N the number of questions in the round, and A the number answered. All three are whole-number question counts, with N greater than zero and 0 ≤ C ≤ A ≤ N. Points equal C, possible points equal N, and the score ranges from zero to N.

The correct-answer percentage and completion progress use the full round length as their denominator.

Score points=C Accuracy (%) = 100 × CN Progress (%) = 100 × AN

The final summary displays the exact count C/N. Accuracy retains its unrounded value. The visible progress label rounds to the nearest whole percent, with half-percent ties rounded upward. During a partial attempt, unanswered questions remain in N, but are not recorded as incorrect or included in missed-answer practice. Completion requires an answer to every selected question.

Questions are selected without replacement from the chosen set, and the seed also determines the offered choices and their order. Definitions and scenarios are separate pools, so a ten-question common-record round covers all ten types in one format, not all 20 prompts. A full pass through both formats requires two rounds.

Privacy Notes:

Answer checking happens in your browser, but an attempt is not private merely because it is scored there. The page URL carries the setup, seed, recorded answers and current position, including partial attempts. Saved responses are encoded, not encrypted. Someone receiving that URL can restore the recorded choices. URLs may enter browser history or be transmitted when loaded or shared, so avoid sensitive information in the replay seed.

Change setup clears the current attempt and its saved state from the current page URL. It does not erase previously shared links or history. There is no account-based progress history, and chart or document features may load third-party resources. Browser-based scoring is not a guarantee of offline operation or no network traffic.

Damaged or incompatible saved attempts are rejected rather than silently treated as a fresh score. If Saved attempt unavailable appears, choose an available set, feedback mode and question count, then select Start practice to begin again.

Worked Examples:

A zone record mistaken for an address

Choose Addresses and names · definitions, four questions, After each answer and replay seed dns-reference-1. Select SOA for the IPv4-address question, then answer the PTR, CNAME and AAAA questions correctly. The final summary is 3/4, equivalent to 75% correct. Addressing has one correct answer and one miss, while Names has two correct answers. The correction identifies A as the address record. Retry missed starts a one-question attempt on that mistake, even though normal setup counts start at two.

Mail routing and sender authorization

Choose Common records · scenarios, ten questions and feedback At the end. When incoming mail must go to a named mail exchanger with preference 10, select MX. When the provider asks where to publish a policy beginning v=spf1, select TXT. Each selection locks without immediate correction. After answering the remaining questions and selecting View results, the ledger marks these two choices correct. Their explanations distinguish delivery routing from authorization to send mail, so they should not be treated as interchangeable records.

References: