iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
DNS records are typed instructions attached to domain names. The type tells a resolver and the consuming application how to interpret the data: an A record supplies an IPv4 address, AAAA supplies IPv6 address data, CNAME names another DNS name, MX identifies mail exchangers, NS identifies authoritative name servers, TXT carries convention-defined text, and SRV describes a service endpoint with selection and port fields. Reading the type before reading the value prevents the most common DNS mistakes.
What a DNS record actually contains
A DNS resource record has an owner name, type, class, TTL (time to live), and RDATA. The owner is the name the record belongs to, such as www.example.com. The type determines the meaning of the RDATA. The class identifies the DNS namespace; Internet records normally use the Internet class. TTL tells caches how long an answer may be retained before the source should be consulted again.
RFC 1035 described TTL this way: “TTL a 32 bit signed integer that specifies the time interval that the resource record may be cached before the source of the information should again be consulted.” That wording describes the original record format. RFC 2181 later clarified TTL handling, so the signed-integer wording should not be treated as current implementation guidance.
The Tool Desk
Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →A resolver may return a cached answer while its TTL has not expired. Consequently, changing a record at the authoritative source does not make every user’s result change at once. Different recursive resolvers may have cached the old answer at different times, and each can continue using it until its own cached TTL expires.
#1 Best Overall
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
- Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
- Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
- 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.
What is an A record?
An A record associates a DNS name with an IPv4 host address. IPv4 addresses use the familiar dotted-decimal form, such as 192.0.2.25 in documentation examples. RFC 1035 assigns A type code 1.
Use an A record when the destination is expressed as an IPv4 address. A web hostname, an application endpoint, or another host name can have an A record, but the record itself says nothing about whether a web server is running, whether a firewall permits traffic, or whether the application is healthy. It only supplies IPv4 address data to software that asks for it.
What is the difference between A and AAAA records?
A and AAAA are both address-record types, but they carry different IP versions. A stores IPv4 data; AAAA stores one IPv6 address as 128-bit data. RFC 9499 groups them as address records, while RFC 3596 defines AAAA and IPv6 support in DNS.
Quick wins for a faster PC:
Repair Windows errors before they cause bigger problemsFix Now →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Clear out junk files and repair common Windows errorsFree Scan →| Record | Address family | RDATA | Specification detail |
|---|---|---|---|
| A | IPv4 | An IPv4 address in dotted-decimal form | Type code 1 in RFC 1035 (1987) |
| AAAA | IPv6 | A 128-bit IPv6 address | Type code 28 in RFC 3596 (2003) |
A name can have multiple AAAA records when it has multiple IPv6 addresses. Asking DNS for AAAA data does not require the DNS query itself to travel over IPv6; a client using IPv4 transport can still request IPv6 address records. Whether a returned address is usable depends on routing, connectivity, firewall policy, and the service listening at that address.
What does a CNAME record do?
A CNAME makes one DNS name an alias for another name, called the canonical name. Its RDATA is a domain name, not an IPv4 or IPv6 address. A resolver follows the alias and then looks up the target’s applicable records.
Rank #2
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
For example, an illustrative record such as app.example.com CNAME service.example.net says “use service.example.net as the canonical name.” It does not embed the target’s IP address, and changing the target’s A or AAAA records changes what clients ultimately obtain without changing the alias text.
When diagnosing an alias, inspect both links: first confirm the CNAME target is the intended name, then query that target for the address or other record the application needs. A CNAME alone does not prove that the target resolves successfully or that the service is reachable.
PC Slower Than It Used to Be?
A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11Crashes, No Sound, or Screen Glitches?
Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minuteWhat are MX records used for?
An MX record identifies a mail exchanger for a domain. Its data contains a preference value and the exchanger’s domain name. Mail-delivery software uses the preference information when choosing among the listed exchanges.
MX is about mail handling, not a website’s address. A domain can have one set of A or AAAA records for web traffic and a different set of MX records for mail. The MX value is a host name; the receiving system then needs address data for that host, normally through A and/or AAAA lookups.
In an example, example.com MX 10 mail.example.net identifies mail.example.net as an exchange with preference value 10. The number is meaningful only within the domain’s set of MX records and does not represent an IP address, a port, or a delivery guarantee.
Rank #3
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
What does an NS record mean?
An NS record names a server that is expected to be authoritative for a domain or zone. NS records are part of DNS delegation: they tell resolvers which name servers hold the authoritative data for the relevant portion of the namespace.
Free tools Windows power users keep installed
One-click scans. No signup required.
NS identifies authority, not the address used to contact that authority. To reach a named server, a resolver separately needs address data for the server’s host name. An NS answer therefore should not be mistaken for an A or AAAA answer, and finding an NS record does not by itself demonstrate that the server is responding correctly.
The terms “DNS server” and “name server” are often used loosely. An authoritative name server publishes the source data for a zone. A recursive resolver accepts a client’s question, follows delegations and referrals, caches answers, and returns a result. One organization can operate both roles, but the roles and responsibilities are different.
What is a TXT record used for?
A TXT record stores one or more text strings. DNS defines the type as text data; a protocol or service gives a particular string its meaning by convention. That makes TXT a general-purpose container rather than a single-purpose instruction.
Applications commonly publish verification tokens, policy text, or other protocol-specific information in TXT records. The correct interpretation always comes from the convention used by the application that requested the record. A TXT value that is meaningful to one service is not automatically meaningful to another, and a syntactically valid TXT record can still contain the wrong content for its intended consumer.
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Scan for outdated or missing drivers - takes under a minute3Clear out junk files and repair common Windows errorsRank #4
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
- Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
- Broad Compatible: The usb c to usb adapter widely supports all USB C/ USB A devices like laptops, tablets, cellphones, car chargers, and phone chargers. Such as compatible with MacBook Pro/Air 2023/2022, Thunderbolt 4/3 Devices,Apple MagSafe Watch 9/8/7/SE/Ultra, iPad Pro 2022/2021, Samsung Galaxy S23/S20/S10, and iPhone 17/16/15 Pro. Plug and play
- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
When checking TXT, copy the value exactly as presented by the DNS management system and query the name at which the consuming protocol expects it. Do not treat a TXT string as an IP address, a mail exchanger, or a service port.
What is an SRV record?
An SRV record publishes where a named service is available. Its structured data includes priority, weight, port, and a target host name. RFC 2782 assigns SRV type code 33.
| SRV field | What it conveys |
|---|---|
| Priority | Ordering information used when more than one service target is available |
| Weight | Selection weighting among targets with the same priority |
| Port | The transport port on which the service is expected to listen |
| Target | The host name clients should contact for that service |
SRV is therefore more than an alias. It can identify a service endpoint and its port, while the target host’s address still comes from address records. An SRV response does not prove that a process is listening, that the port is reachable through a firewall, or that the service accepts the client’s request.
How the record types differ in practice
When you encounter an unfamiliar DNS entry, identify the question it answers before reading its value.
Recommended Free Tools
| Question | Record type | Data interpreted as | Primary consumer |
|---|---|---|---|
| What IPv4 address belongs to this name? | A | IPv4 address | Clients and applications using IPv4 |
| What IPv6 address belongs to this name? | AAAA | 128-bit IPv6 address | Clients and applications using IPv6 |
| Which other DNS name is this an alias for? | CNAME | Canonical domain name | Resolvers following aliases |
| Where should mail for this domain be delivered? | MX | Preference plus exchanger name | Mail-transfer software |
| Which servers are authoritative for this zone? | NS | Authoritative name-server names | Resolvers performing delegation |
| What text does a protocol or service publish here? | TXT | Text strings | The protocol or service defining the convention |
| Where is this named service listening? | SRV | Priority, weight, port, and target name | Clients that implement service discovery |
How to interpret a DNS record step by step
- Start with the owner name. Confirm whether the question concerns the zone apex, a host such as
www, a mail name, or a service-specific name. - Read the type before the value. The same-looking string has different implications depending on whether it appears in A, CNAME, MX, TXT, NS, or SRV RDATA.
- Separate names from addresses. CNAME, MX, NS, and SRV contain names that may require additional A or AAAA lookups. They do not become IP addresses merely because a client eventually connects to one.
- Check selection fields. MX uses a preference value; SRV uses priority and weight in addition to its port and target. Do not compare those numbers as if they were IP addresses or TTLs.
- Account for caching. Record the TTL shown with the answer and consider when the resolver cached it. A recently edited authoritative record can coexist with an older cached response until expiration.
- Verify the consuming system. DNS supplies data; mail software, a web client, or a service-discovery implementation decides how to use it. Confirm the application protocol and network path separately.
Common mistakes and how to troubleshoot them
Expecting an edit to appear immediately
If one resolver shows the new value and another shows the old value, compare their cached TTLs and query times. The authoritative source may already be correct while recursive caches are still within their allowed lifetime. Repeating the edit does not force every cache to discard its answer.
Best Value
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
Putting an IP address in a CNAME
A CNAME’s data must name a canonical DNS name. If the intended destination is an address, use the appropriate A or AAAA record at the name that should answer the address query. If the design requires an alias, point the CNAME to a name and inspect that name’s address records.
Using a web address as an MX value
MX identifies mail exchangers, not website destinations. Check that the MX target is the host intended to receive mail and then verify that the target name has usable address data. A working website A record does not establish correct mail routing.
Treating NS as an IP-address answer
NS tells you which host names are authoritative. Resolve those host names separately when you need their addresses, and distinguish the authoritative response from a recursive resolver’s cached response.
Assuming TXT has one universal meaning
Read the protocol or service documentation that requested the TXT value. A token, policy string, and verification value can all be valid TXT data but are not interchangeable.
Assuming SRV proves reachability
SRV supplies a target and port according to its priority and weight. Test the resulting network path and application separately; firewalls, routing, listeners, and authentication can still prevent a connection.
What DNS records can—and cannot—tell you
Records answer narrowly defined naming and discovery questions. A and AAAA provide address data; CNAME provides an alias relationship; MX provides mail-exchange selection; NS identifies authority; TXT carries convention-defined text; and SRV provides structured service location. None of these records alone confirms that a host is online, a port is open, a server is authoritative in practice, mail will be accepted, or an application is correctly configured. Those outcomes depend on the systems and networks behind the DNS data.
Keeping the record type, its RDATA format, its TTL, and the role of the querying system separate gives you a reliable way to read DNS without confusing an address with an alias, mail routing with web hosting, authority with reachability, or free-form text with service discovery.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
