--- title: DNS Records for Your Domain: A, MX, CNAME, TXT url: https://hdiss.net/guides/dns-records-for-your-domain/ business: High Desert Internet Services (HDISS) phone: 775-575-9593, 775-391-5660 email: info@hdiss.net mailing_address: Home base: 200 S Virginia St, Suite 760, Reno NV 89501 (dispatch office, not a walk-in store). Mail: Billing Dept., PO Box 11353, Reno NV 89510 hours: Office open 9:00 AM to 5:00 PM, seven days a week. Network watched around the clock. type: Fixed wireless internet service provider (homes and small businesses), web hosting, customer email, domain registration service_area: Northern Nevada - Washoe, Lyon, Storey, Churchill and Douglas counties and Carson City; availability is checked address by address (line of sight to a tower) plans: Bronze $50/mo up to 500 Mbps down, up to 200 Mbps up; Silver $75/mo up to 800 down, up to 200 up; Gold $99/mo up to 1 Gig down, up to 200 up; ask about the up to 1 Gig / 1 Gig ultra-low-latency service no_online_purchase: true (check your address or call; existing customers pay at https://www2.fernley.net/hdiss/onlinepay/paymentform.cfm) since: 2002 --- - [Home](https://hdiss.net/) - [Guides](https://hdiss.net/guides/) - DNS records for your domain: A, MX, CNAME and TXT explained # DNS Records for Your Domain: A, MX, CNAME and TXT Explained DNS records are the entries in your domain's address book: an A record points a name to a server address, MX says where mail goes, CNAME makes one name an alias for another, NS lists who answers for the domain, and TXT holds text such as email authentication rules. A Wi-Fi router on a shelf. Stock photo: Adobe Stock. [Photo credits](https://hdiss.net/photo-credits/) On this page - [What is in the address book?](#what-is-in-the-address-book) - [Which record does what for a small business?](#which-record-does-what-for-a-small-business) - [What are the limits and quirks?](#what-are-the-limits-and-quirks) - [How to change records safely](#how-to-change-records-safely) - [What can High Desert say?](#what-can-high-desert-say) When someone says to change your DNS, they mean editing these entries at the company that hosts your domain's records. Get one wrong and the website or the email stops. This guide explains the record types from the standards that define them, and gives a short routine for changing them safely. The examples use example.com and a documentation address. ## Takeaways - RFC 1035 defines A (type 1, a host address), NS (2, an authoritative name server), CNAME (5, the canonical name for an alias), MX (15, mail exchange) and TXT (16, text strings). - Domain labels are limited to 63 octets and names to 255 octets (RFC 1035). - RFC 7208 says SPF records must be published as DNS TXT records. - Registrar and DNS host can be different companies; check where your records live before you edit. ## What is in the address book? The Domain Name System turns names into the data computers need. The original specification, RFC 1035, lists the record types by number. An A record (type 1) is “a host address”: it ties a name like www.example.com to an IPv4 address such as 203.0.113.10, a number from the range set aside for examples. An NS record (type 2) names an authoritative name server, the computers that answer for your domain. A CNAME (type 5) is “the canonical name for an alias”: it says that one name is another name. An MX record (type 15) is the mail exchange: where email for your domain should be delivered. A TXT record (type 16) holds text strings. Each record has a TTL, the time in seconds that others may keep a copy before asking again. A short TTL makes changes show up sooner. ## Which record does what for a small business? Use this map: - Website: an A record for example.com and for www.example.com pointing to your web host's address, or a CNAME from www to the main name. The host will tell you which. - Email: MX records pointing to your mail provider, with a priority number; the lowest number is tried first. One wrong MX and mail goes to the wrong place. - Email authentication: TXT records. RFC 7208 states that SPF records “MUST be published as a DNS TXT (type 16) Resource Record,” for example a line beginning v=spf1. See [the deliverability guide](https://hdiss.net/guides/email-deliverability-spf-dkim-dmarc/). - Proof of ownership: many services ask you to add a TXT record with a code, to show you control the domain. - Name servers: NS records tell the world which company holds the rest of your records. They are set at your registrar. ## What are the limits and quirks? RFC 1035 limits a label, the piece between dots, to 63 octets, and a whole name to 255 octets. A CNAME cannot live beside other records for the same name, so the bare domain, example.com, usually takes an A record and not a CNAME. And RFC 7208 section 4.6.4 caps an SPF check at 10 terms that cause DNS lookups, such as include, a and mx; go over it and the check returns an error, which is a reason to keep the SPF line short when you add senders. ## How to change records safely Follow this routine: - Find where your records are hosted. The registrar where you bought the name is often, but not always, the DNS host; ICANN advises always keeping your registrant account information private, secure and recoverable. - Copy every existing record to a text file before you change anything. - Change one thing at a time. Lower the TTL a day ahead if you plan a move. - Test with the service's own check, send a test email, and load the website from another network, such as a phone on cellular. - Keep the old records for a few days in case you need to switch back. ## What can High Desert say? High Desert lists domain registration, web hosting and email among its services, and customer email uses the hosts pop.hdiss.net and smtp.hdiss.net with the full email address as the username. How it handles DNS for customer domains is not published here, so ask when you call 775-575-9593 any day from 9 to 5. Our guides on [what a domain name is](https://hdiss.net/guides/what-is-a-domain-name/), [moving a website](https://hdiss.net/guides/moving-a-website-to-a-new-host/) and [email on your own domain](https://hdiss.net/guides/email-on-your-own-domain/) show where DNS fits. If you are choosing a provider, send your address through the check form. A person looks at the path from the nearest tower and calls you back, and you can ask about hosting and domains on that call. ### Sources - [rfc-editor.org/rfc/rfc1035](https://www.rfc-editor.org/rfc/rfc1035) (RFC 1035, Domain Names: Implementation and Specification, read 10/15/26) - [rfc-editor.org/rfc/rfc7208](https://www.rfc-editor.org/rfc/rfc7208) (RFC 7208, Sender Policy Framework, April 2014, read 10/15/26) - [icann.org/en/blogs/details/do-you-have-a-domain-name-heres-what-you-need-to-know-30-4-2020](https://www.icann.org/en/blogs/details/do-you-have-a-domain-name-heres-what-you-need-to-know-30-4-2020-en) (ICANN, Do You Have a Domain Name, April 30, 2020, read 10/15/26) ### Talk to a person - Call [775-575-9593](tel:7755759593) [775-391-5660](tel:7753915660) Open 9-5 every day - Email [info@hdiss.net](mailto:info@hdiss.net) [Check my address](https://hdiss.net/check-availability/#check) Local since 2002 Fixed wireless from towers in Northern Nevada. Three plans, no contracts, local support, 4.8 on Google from 36 reviews. [About High Desert](https://hdiss.net/about/) ### Keep reading - [What a domain name is and who owns it](https://hdiss.net/guides/what-is-a-domain-name/) - [Why business email lands in spam: SPF, DKIM and DMARC](https://hdiss.net/guides/email-deliverability-spf-dkim-dmarc/) - [Moving a website to a new host](https://hdiss.net/guides/moving-a-website-to-a-new-host/) - [Email on your own domain: how hosting, email and domains fit together](https://hdiss.net/guides/email-on-your-own-domain/) - [Choosing a domain name for a local business](https://hdiss.net/guides/choosing-a-domain-name/) ## More on email and hosting how-to - [POP3 vs IMAP in plain words](https://hdiss.net/guides/pop3-vs-imap/): POP3 downloads your mail to one device and normally removes it from the server; IMAP leaves the mail on the server so every device sees the same inbox. High Desert Internet's customer email uses a POP3 server, pop.h - [Keeping email when you change devices](https://hdiss.net/guides/keeping-email-when-you-change-devices/): Before you retire the old phone or computer, turn on the setting that leaves a copy of mail on the server, copy or export what is stored on the old device and check what shows in webmail. High Desert's mail uses POP - [What a domain name is and who owns it](https://hdiss.net/guides/what-is-a-domain-name/): A domain name is the address people type to reach your website and the ending of your email addresses, registered through a company called a registrar. The person or business named as the registrant holds it, and keeps i ## Questions people ask ### Can I break my website by editing DNS? Yes, which is why you copy the old records first. Most changes can be reversed by restoring the copy. ### Why do changes take time to show? Others keep a copy of each record for its TTL. After that time they ask again and see the change.