- Determine which of the following is an FQDN and which is a PQDN.
a. xxx
b. xxx.yyy.
c. xxx.yyy.net
d. zzz.yyy.xxx.edu.
- Determine which of the following is an FQDN and which is a PQDN.
a. mil.
b. edu.
c. xxx.yyy.net
d. zzz.yyy.xxx.edu
The Correct Answer and Explanation is :
1. Determining FQDN vs. PQDN:
a. xxx
This is a PQDN (Partially Qualified Domain Name). A PQDN is typically a domain name that is not fully specified (i.e., lacks a complete path to the root domain). “xxx” only contains a single label, so it is incomplete.
b. xxx.yyy.
This is also a PQDN. The trailing period suggests it might represent a fully qualified name (FQDN), but since it lacks a top-level domain (TLD) such as .com, .org, etc., it is still considered a PQDN.
c. xxx.yyy.net
This is an FQDN (Fully Qualified Domain Name). It contains a fully specified domain with multiple labels, including the second-level domain (yyy) and the top-level domain (.net).
d. zzz.yyy.xxx.edu.
This is an FQDN. It has multiple labels: zzz, yyy, xxx, and edu, which make it fully qualified and specifies the exact domain. The trailing period makes it explicitly complete, signaling that it’s a fully qualified domain.
2. Determining FQDN vs. PQDN:
a. mil.
This is a TLD (Top-Level Domain), not an FQDN or PQDN by itself. However, when it stands alone as a domain, it’s neither fully qualified nor partially qualified—it is simply the TLD “mil.”
b. edu.
Like “mil.”, this is a TLD. It represents a top-level domain used in domains of educational institutions. By itself, it’s not qualified in any way.
c. xxx.yyy.net
This is an FQDN. The domain consists of xxx (second-level domain), yyy (subdomain), and .net (top-level domain), which is a fully specified domain name.
d. zzz.yyy.xxx.edu
This is also an FQDN. It contains the fully qualified domain name with the structure of zzz.yyy.xxx.edu, representing a complete path to the root domain, making it fully qualified.
Explanation:
An FQDN is a complete and unique domain name that specifies the exact location of a resource in the Domain Name System (DNS). It includes a domain name and its path to the root DNS, ending with a period, representing its full specification (e.g., www.example.com.). A PQDN, on the other hand, is incomplete and does not specify the full path to the root domain. It may lack the TLD or other parts needed to fully resolve to an internet address (e.g., example.com without the root DNS designation).