Glossary of Domain-Related Terms

TLD

A top-level domain is either a gTLD or a ccTLD. For all domains, a TLD is the last part of the domain name, what comes after the last dot. Some interpret gTLDs and ccTLDs by themselves as TLDs (correct), and others interpret a domain registered directly below a TLD (e.g. google.com) as a TLD (incorrect). Domains that aren't TLDs are subdomains (e.g. .co.cc), but sometimes, what seems like a subdomain is actually a TLD (e.g. .co.uk). Find further discussion on the difference between domains vs. subdomains in this article.

gTLD

A generic top-level domain. The list consisted initially of .com, .net, .org, .edu, .gov, and .mil, but has since expanded for .int, .aero, .biz, .coop, .info, .museum, .name, .pro, .asia, .cat, .jobs, .mobi, .tel, .travel, and .xxx. If you want to see examples of sites using these TLDs, you only need to search Google with 'site' parameter, for instance, site:travel. Some of those domains are sponsored TLDs, which means you may need to go through special measures to (not) obtain one. Sometime after 2012, it is expected the list to expand to thousands of generic TLDs, mostly reflecting names of companies and products, but also generic names like .bank, .food, .wine, ... You can follow the list of new applicants on registries.tel.

ccTLD

A country code top-level domain is a TLD generally used or reserved for a country. ccTLDs are two characters long, and they (mostly) correspond to ISO 3166 alpha-2 country codes. Most free (sub)domains on our list are ccTLDs, but that doesn't you can't use them if your country doesn't match. Luckily, Google and other search engines understand that some ccTLDs are often used in "domain hacks", such as goo.gl, del.icio.us, please.do.not.disturb.me, which means they don't pertain to particular country but have a wider audience, so they treat them as gTLDs. These domains have a green checkmark (yes) sign in the Geo column in our list, meaning they are geo-targetable.

IDN

Internationalized domain names are those that contain at least one language-specific non-ASCII script or character. For example, domains with characters from Arabic or Chinese alphabets are IDNs. Klær.no is an example of a Norwegian IDN. Some domain providers from our list support IDNs, and those that do are marked accordingly in the IDN column. Note that they may not support Unicode characters directly, e.g. registering "škratče" domain may not work. In that case, you first have to convert your domain to Punycode (e.g. "škratče" becomes "xn--krate-kya79c"). You can convert normal text to punycode here. In your browser, you can access the website normally, though.

Punycode

See IDN.

Geo-Targeting

Geo-Targeting is a feature of Google Webmaster Tools, where a webmaster can set his domains as targeting a particular country. All gTLDs are GeoTargetable, but so are only some vanity ccTLDs, those that are commonly used in domain hacks. For example, a .com domain can be, as a gTLD, targeted to one specific country, or instead no country in particular. So can .tk or .cc (sub)domain. But .ie domain cannot be geo-targeted and is only automatically targeted at people of Ireland. If a domain is geo-targeted, that means it will show up more often in that country's version of Google or search query limited to that language (e.g. google.de or searching in German language for a German .de domain, which is is not geo-targetable to other countries). Read more about Google's geotargeting here. In our list, geo-targetable domains are marked with a green checkmark (yes) in the Geo column.

DNS records

The Domain Name System (DNS) is a hierarchical, distributed naming system that translates human-readable domain names and hostnames to machine-readable numbers such as IP addresses. Some common DNS record types:

A

Holds a 32-bit IP address. The domain answers to the server at this address.

AAAA

Holds 128-bit IPv6 address.

CNAME

Alias of one domain name to another.

MX

Mail eXchange record maps domain to prioritized list of message (email) transfer agents for that domain.

NS

Delegates a DNS zone to use the given name servers.

SOA

Usually specifies authoritative information about a DNS zone, e.g. the primary name server, the administrator email, the domain serial number, and several timers related to refreshing the zone.

TXT

Originally, TXT record stored arbitrary human-readable text in a DNS zone, but nowadays more often carries machine-readable data.

Age

In our comparison table, the column Age represents the number of years of current free service. As with wiskey perhaps, the longer it matures, the better it becomes. Some free domain providers are more reliable than others, some have reputation to uphold. Others may disappear without notice. You wouldn't want to be hosted under one of those, would you?

Indexed

If the subdomains of a particular domain registrar are present in the Google Search index, then they have a green checkmark (yes) in that field. Contrary, if the whole domain including all subdomains is banned, that means it is not currently indexed, so the field flag is a red cross (no).
It is important to realize that these bans are temporary and last anywhere from 90 days to couple of years. The latest such ban was imposed in July 2011, likely part of continuing improvements on Google Panda updates. It probably wasn't the last of its kind, at least until spammers stop taking advantage, or more likely, until the providers get to identify the threats and issues sooner and curb them more efficiently.

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