A domain name is text representation of an IP address. When a user enters a URL their device will use a DNS resolution service. The DNS resolver service will look up the corresponding IP address for the domain name.
blog.martincox.dev → 18.133.18.119Cloudflare and google offer public DNS servers. These are free to use. Whereas AWS offer a paid DNS server (Route 53 service).
Note that the above mapping is a ‘A’ type. An ‘A’ type record matches a domain name to an IP address.
Other common record types:
| Type | Purpose |
|---|---|
| A | Maps a domain → IPv4 address |
| CNAME | Alias of another hostname. For example: blog.martincox.dev → ghs.googlehosted.com |
| MX | Links an email address to an email server |
Various organisations control .com, .co.uk, .co.nz these appended endings are called top-level domains. The companies which control the master list of these domains are called Registries.
Domain names are purchased via Registrars. Examples being GoDaddy, and Cloudflare.
The Registries set the wholesale price, the Registrars typically add a mark up on top. Cloudflare do not add any markup. Some TLDs which are commercially desirable command a price premium such as .bank, and .law.
Questions to answer:
- Who are the TLD organisations? How do they make money?
There are 1500, some are government run. They make money by charging a wholesale fee for every domain created, renewed or transferred.
- When I buy a domain name via Cloudflare, do they deal directly with the TLD organisation?
Yes, they are authorised to register/renew domains directly with registries.
- When I purchased a domain name I had to give my name and address, why was this required?
For legal reasons, for example if the website owner needs to be contacted for breaking copyright. The information used to be available publicly, but due to GDPR regulation this is no longer the case.
- Any famous cases of large companies failing to register a domain, or losing their domain.
google.com was not renewed, in 2015. Google later required it for $6k USD
- Different TLDs have become available in recent years, .io, .dev etc, why is this?
ICANN began to allow organisations to become TLD operators for a fee in 2013. This was partly done due to the saturation of the .com domain. And to increase revenue.
- What does .com stand for, and why has it become the defacto TLD
.com stands for commercial and was one of the originally launched TLDs in 1985. They had a first mover advantage.
- How do changes propagate through DNS servers, if I change the static IP address assigned to my domain, how long will this take to come into effect.
Instantly on Cloudflare, but depending on other servers, and cache settings -> between 5-30 minutes.
- How does one transfer ownership of a domain name in the resellers market.
One unlocks the domain at their registrar, and provides an associated authentication code to the buyer. For buyer seller trust an escrow service is typically used.
- Do some TLDs require additional verification?
For some you must be a government, or educational institution. For others you may be required to prove residency/citizenship
- Who is ICANN
ICANN is the Internet Corporation for Assigned Names and Numbers. They oversea all Registries. They do not directly sell domain names; they authorise resellers.
- For servers where access is typically M2M (machine to machine), would it be better to simply use an IP address?
You risk all devices being bricked if the IP address were to change. Using the DNS system also allows the possibility of using load balancers for large deployments.
- What happens if you have an IoT product and schedule an update to 50k+ devices, will the DNS server remain responsive.
If your product cache’s the DNS result, then generally this should not be an issue. However, if your baseline number of DNS queries increases above baseline subsequent DNS queries may be throttled or dropped. Especially as your MNO (mobile network operator) will all appear from the same IP address range.
Keywords:
Authoritative DNS, WHOIS/RDAP records, ICANN, authoritative DNS servers, DNS root zone