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Planet Argon Planet Argon Engineering Handbook

Understanding Domain Name System (DNS)

Background

Section titled “Background”

The official description of the Domain Name System (DNS) is: a hierarchical and decentralized naming system for computers, services, or other resources connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities. (Thanks, Wikipedia!)

You can think of DNS like the contact list on your smartphone. Just as you don’t need to memorize your friends’ phone numbers because you have them saved under names you can easily remember, DNS saves you the hassle of memorizing IP addresses. It maps human-readable domain names, like www.google.com, to their machine-readable IP addresses, like 8.8.8.8.

DNS is designed to be decentralized. This decentralization is crucial because it adds layers of redundancy and resilience against system failure. If one DNS server goes down, the system can quickly reroute queries to another available server, ensuring the smooth operation of the Internet.

Wait, What is a Domain Name?

Section titled “Wait, What is a Domain Name?”

A domain name is a human-friendly address that you type into your web browser. A domain name is usually made up of three components: subdomain.domain.TLD. For example, in www.google.com, www is the subdomain, google is the domain, and com is the Top-Level Domain (TLD).

What About Sub-Domains?

Section titled “What About Sub-Domains?”

Sub-domains serve more functions than just “nesting.” Different sub-domains can be mapped to different IP addresses. This versatility is beneficial for load balancing, regional distribution, and more. For example, us.amazon.com and uk.amazon.com could route traffic to servers in the United States and the United Kingdom, respectively.

We use sub-domains a lot in our work. We often use a staging subdomain on a client site to test changes before they are shipped to production. We also use them to nest certain sections of a website for structural or categorical reasons, such as blog.planetargon.com, or portland.craigslist.org.

How Does DNS Work?

Section titled “How Does DNS Work?”

When you type a domain name into your browser, several servers work together to resolve it to an IP address. Initially, a DNS query is sent to a recursive resolver. If needed, this query gets forwarded to authoritative servers, which ultimately provide the final IP address. Various query types exist, such as A, AAAA, CNAME, and MX, serving different purposes from basic IP address retrieval to mail exchange routes.

There’s a lot more that goes into DNS than this summary can cover. For a more thorough explanation, checkout any of these great resources:

Debugging DNS

Section titled “Debugging DNS”

Here are a few tips for debugging DNS-related issues:

  • Use the dig command to lookup DNS info for a host name

    For Linux and macOS users, the dig command can be quite handy. Windows users can use nslookup for similar functionality. When you run a dig command, you may receive output like d1oog6b7224omr.cloudfront.net followed by IP addresses. This indicates the domain and its corresponding resolved IP.

    Remember that DNS queries can sometimes be cached. If you’re facing issues, ensure that you clear your DNS cache, as this can significantly impact debugging.

  • Use a WHOIS lookup tool in your terminal to find out who owns a domain

Terminal window
➜  ~ whois planetargon.com
% IANA WHOIS server
% for more information on IANA, visit http://www.iana.org
% This query returned 1 object


refer:        whois.verisign-grs.com


domain:       COM


organisation: VeriSign Global Registry Services
address:      12061 Bluemont Way
address:      Reston VA 20190
address:      United States of America (the)


contact:      administrative
name:         Registry Customer Service
organisation: VeriSign Global Registry Services
address:      12061 Bluemont Way
address:      Reston VA 20190
address:      United States of America (the)
phone:        +1 703 925-6999
fax-no:       +1 703 948 3978
e-mail:       info@verisign-grs.com


contact:      technical
name:         Registry Customer Service
organisation: VeriSign Global Registry Services
address:      12061 Bluemont Way
address:      Reston VA 20190
address:      United States of America (the)
phone:        +1 703 925-6999
fax-no:       +1 703 948 3978
e-mail:       info@verisign-grs.com


nserver:      A.GTLD-SERVERS.NET 192.5.6.30 2001:503:a83e:0:0:0:2:30
nserver:      B.GTLD-SERVERS.NET 192.33.14.30 2001:503:231d:0:0:0:2:30
nserver:      C.GTLD-SERVERS.NET 192.26.92.30 2001:503:83eb:0:0:0:0:30
nserver:      D.GTLD-SERVERS.NET 192.31.80.30 2001:500:856e:0:0:0:0:30
nserver:      E.GTLD-SERVERS.NET 192.12.94.30 2001:502:1ca1:0:0:0:0:30
nserver:      F.GTLD-SERVERS.NET 192.35.51.30 2001:503:d414:0:0:0:0:30
nserver:      G.GTLD-SERVERS.NET 192.42.93.30 2001:503:eea3:0:0:0:0:30
nserver:      H.GTLD-SERVERS.NET 192.54.112.30 2001:502:8cc:0:0:0:0:30
nserver:      I.GTLD-SERVERS.NET 192.43.172.30 2001:503:39c1:0:0:0:0:30
nserver:      J.GTLD-SERVERS.NET 192.48.79.30 2001:502:7094:0:0:0:0:30
nserver:      K.GTLD-SERVERS.NET 192.52.178.30 2001:503:d2d:0:0:0:0:30
nserver:      L.GTLD-SERVERS.NET 192.41.162.30 2001:500:d937:0:0:0:0:30
nserver:      M.GTLD-SERVERS.NET 192.55.83.30 2001:501:b1f9:0:0:0:0:30
ds-rdata:     30909 8 2 e2d3c916f6deeac73294e8268fb5885044a833fc5459588f4a9184cfc41a5766


whois:        whois.verisign-grs.com


status:       ACTIVE
remarks:      Registration information: http://www.verisigninc.com


created:      1985-01-01
changed:      2023-09-12
source:       IANA


# whois.verisign-grs.com


   Domain Name: PLANETARGON.COM
   Registry Domain ID: 89598895_DOMAIN_COM-VRSN
   Registrar WHOIS Server: whois.1api.net
   Registrar URL: http://www.1api.net
   Updated Date: 2023-11-08T12:11:32Z
   Creation Date: 2002-08-23T05:35:49Z
   Registry Expiry Date: 2024-08-23T05:35:52Z
   Registrar: 1API GmbH
   Registrar IANA ID: 1387
   Registrar Abuse Contact Email: abuse@1api.net
   Registrar Abuse Contact Phone: +49.68949396850
   Domain Status: clientTransferProhibited https://icann.org/epp#clientTransferProhibited
   Name Server: NS1.DNSIMPLE.COM
   Name Server: NS2.DNSIMPLE-EDGE.NET
   Name Server: NS3.DNSIMPLE.COM
   Name Server: NS4.DNSIMPLE-EDGE.ORG
   DNSSEC: unsigned
   URL of the ICANN Whois Inaccuracy Complaint Form: https://www.icann.org/wicf/
>>> Last update of whois database: 2023-11-21T00:13:28Z <<<


# whois.1api.net




Domain Name: PLANETARGON.COM
Registry Domain ID: 89598895_DOMAIN_COM-VRSN
Registrar WHOIS Server: whois.1api.net
Registrar URL: http://www.1api.net
Updated Date: 2023-11-08T12:11:32Z
Creation Date: 2002-08-23T05:35:49Z
Registrar Registration Expiration Date: 2024-08-23T05:35:52Z
Registrar: 1API GmbH
Registrar IANA ID: 1387
Registrar Abuse Contact Email: abuse@1api.net
Registrar Abuse Contact Phone: +49.68949396x850
Domain Status: clientTransferProhibited - http://www.icann.org/epp#clientTransferProhibited
Registry Registrant ID:
Registrant Name: REDACTED FOR PRIVACY
Registrant Organization: REDACTED FOR PRIVACY
Registrant Street: REDACTED FOR PRIVACY
Registrant City: REDACTED FOR PRIVACY
Registrant State/Province: Oregon
Registrant Postal Code: REDACTED FOR PRIVACY
Registrant Country: US
Registrant Phone: REDACTED FOR PRIVACY
Registrant Phone Ext:
Registrant Fax:
Registrant Fax Ext:
Registrant Email: contact via https://www.1api.net/send-message/planetargon.com/registrant
Registry Admin ID:
Admin Name: REDACTED FOR PRIVACY
Admin Organization: REDACTED FOR PRIVACY
Admin Street: REDACTED FOR PRIVACY
Admin City: REDACTED FOR PRIVACY
Admin State/Province: REDACTED FOR PRIVACY
Admin Postal Code: REDACTED FOR PRIVACY
Admin Country: REDACTED FOR PRIVACY
Admin Phone: REDACTED FOR PRIVACY
Admin Phone Ext:
Admin Fax:
Admin Fax Ext:
Admin Email: contact via https://www.1api.net/send-message/planetargon.com/admin
Registry Tech ID:
Tech Name: REDACTED FOR PRIVACY
Tech Organization: REDACTED FOR PRIVACY
Tech Street: REDACTED FOR PRIVACY
Tech City: REDACTED FOR PRIVACY
Tech State/Province: REDACTED FOR PRIVACY
Tech Postal Code: REDACTED FOR PRIVACY
Tech Country: REDACTED FOR PRIVACY
Tech Phone: REDACTED FOR PRIVACY
Tech Phone Ext:
Tech Fax:
Tech Fax Ext:
Tech Email: contact via https://www.1api.net/send-message/planetargon.com/tech
Name Server: ns1.dnsimple.com 162.159.24.4 2400:cb00:2049:0001:0000:0000:a29f:1804
Name Server: ns2.dnsimple-edge.net 199.247.153.53 2620:0111:8005:0000:0000:0000:0000:0053
Name Server: ns3.dnsimple.com 162.159.26.4 2400:cb00:2049:0001:0000:0000:a29f:1a04
Name Server: ns4.dnsimple-edge.org
DNSSEC: unsigned
URL of the ICANN WHOIS Data Problem Reporting System:
http://wdprs.internic.net/
>>> Last update of WHOIS database: 2023-11-21T00:13:42Z <<<

NOTE! When you perform a whois search, the results can be overwhelming. What’s essential to focus on are the Name Servers listed, as they are crucial in understanding which servers are authoritative for the domain you’re interested in.