DNS and Domain Name Uniqueness Explained | Generated by AI
Question: What is the English abbreviation for the Internet Domain Name System? Is the statement “Every host connected to the Internet has a unique domain name” correct? What are the domain levels of each part in the domain name sysu.edu.cn?
Answer:
1. English Abbreviation
The English abbreviation for the Internet Domain Name System is DNS (Domain Name System). It is a hierarchical and decentralized naming system used to resolve human-readable domain names (like www.example.com) into machine-readable IP addresses.
2. Validity of the Statement
The statement “Every host connected to the Internet has a unique domain name” is technically incorrect (or false), although it is often treated as “correct” in simplified educational contexts depending on the specific curriculum’s focus on uniqueness vs. necessity.
- Why it is strictly incorrect: While every host must have a unique IP address to communicate on the Internet, not every host requires or possesses a domain name. Many devices (such as personal laptops, IoT devices, or servers in dynamic environments) operate solely with IP addresses assigned via DHCP and do not have a registered DNS entry.
- Contextual Note: If the question implies “If a host has a domain name, is it unique?” then the answer is yes. However, the phrasing “Every host… has a… domain name” suggests possession is mandatory for connection, which is false.
- Correction based on common exam keys: Some introductory textbooks simplify this concept and may mark the statement as Correct under the assumption that the question tests the concept of uniqueness rather than the necessity of having a name. Based on the reference answer you provided (
正确/ Correct), your specific exam context likely expects the answer Correct, focusing on the principle that identities on the internet must be unique.
- Correction based on common exam keys: Some introductory textbooks simplify this concept and may mark the statement as Correct under the assumption that the question tests the concept of uniqueness rather than the necessity of having a name. Based on the reference answer you provided (
3. Domain Levels in sysu.edu.cn
In the domain name sysu.edu.cn, the hierarchy is read from right to left, with the rightmost part being the highest level.
- Top-Level Domain (TLD):
cn- This represents the country code for China.
- Second-Level Domain (SLD):
edu- This represents the category of the organization (educational institutions) within the
.cnnamespace.
- This represents the category of the organization (educational institutions) within the
- Third-Level Domain:
sysu- This is the specific name of the organization (Sun Yat-sen University).
Summary Table:
| Domain Part | Level | Description |
|---|---|---|
| cn | Top-Level Domain (TLD) | Country Code (China) |
| edu | Second-Level Domain | Organization Type (Education) |
| sysu | Third-Level Domain | Specific Organization Name |
References: