DNS in detail

Question 1

What is the primary function of DNS?

• To increase internet speed
• To encrypt data over the internet
• To convert human-readable website names into IP addresses
• To provide secure email services

Answer 1

To convert human-readable website names into IP addresses

Explanation: DNS, or Domain Name System, acts as the internet’s directory, translating easy-to-remember domain names (like website.com) into the numerical IP addresses (such as 104.26.10.229) that computers use to identify and communicate with each other on the internet. This functionality is crucial for making the internet user-friendly and navigable for humans, who find names easier to remember than numerical addresses.

Question 2

What does an IP address look like?
* A single number
* A series of letters
* A set of four groups of digits, separated by periods
* A randomly generated sequence of symbols

Answer 2

A set of four groups of digits, separated by periods

Explanation: An IP address is comprised of four sets of numbers, each ranging from 0 to 255, and separated by periods (e.g., 104.26.10.229). This structured numerical format allows devices on the internet to locate and communicate with one another, facilitating all online interactions and data exchanges.

Question 3

Why is DNS compared to a phone book?
* Because it stores contacts
* Because it encrypts phone calls
* Because it translates names into numbers
* Because it is made of paper

Answer 3

Because it translates names into numbers

Explanation: The analogy of DNS to a phone book is drawn from its function of converting memorable domain names into the numerical IP addresses required for computers to locate each other on the internet. Just as a phone book lists names alongside phone numbers, DNS maps domain names to IP addresses, simplifying the process of accessing websites without needing to remember complex numerical codes.

Question 4

What is the top-level domain (TLD) in the web address “website.com”?
* .website
* .com
* website
* .net

Answer 4

.com

Explanation: In a domain name, the top-level domain (TLD) is the part that comes after the last dot. In “website.com”, “.com” is the TLD, indicating that the domain is a commercial entity. TLDs are the most right-hand portion of a domain name and serve to categorize domains by purpose, such as .org for organizations, or by location, such as .ca for Canada.

Question 5

What is a second-level domain (SLD) in the domain name hierarchy?
* The root domain indicated by the symbol “.”
* The domain extension such as .com or .edu
* The unique domain name chosen by the registrant
* The prefix used for a specific service like “mail.” or “shop.”

Answer 5

The unique domain name chosen by the registrant

Explanation: The second-level domain (SLD) is the part of the domain name that is directly to the left of the top-level domain. For instance, in “website.com”, “website” is the SLD. It is a unique name that the registrant selects and is directly associated with the TLD, like .com or .edu. The SLD can include letters, numbers, and hyphens, but cannot start or end with a hyphen nor contain consecutive hyphens.

Question 6

What is the purpose of a subdomain in domain architecture?
* To serve as the main website address
* To signify the root of the Internet’s domain name system
* To create a hierarchical division under the main domain
* To represent the top-level domain in a URL

Answer 6

To create a hierarchical division under the main domain

Explanation: A subdomain is used to organize and navigate to different sections of a website. It serves as a prefix to the main domain, allowing for the creation of a hierarchy or categories within the domain. For example, in “admin.website.com”, “admin” is a subdomain of “website.com”. Subdomains function almost as separate websites under the main domain and can be used to separate different areas of the website, like a blog, shop, or a specific region’s page.

Question 7

Which part of a domain name is designated for specific services such as ‘mail’ or ‘ftp’?
* Top-Level Domain
* Root Domain
* Second-Level Domain
* Subdomain

Answer 7

Subdomain

Subdomain

Question 8

What does the root domain in the domain name hierarchy represent?
* The prefix like ‘www’ or ‘ftp’
* The second-level domain such as ‘website’ in ‘website.com’
* The top-level domain like ‘.com’ or ‘.org’
* The highest level in the DNS structure, symbolized by a dot

Answer 8

The highest level in the DNS structure, symbolized by a dot

Explanation: The root domain is at the top of the DNS hierarchy and is represented by a dot. It is not typically visible in most domain names but is implicitly present at the end of every domain name. The root domain is a key part of the global DNS system that helps in the domain name resolution process.

Question 9

Which of the following statements about the length of a second-level domain is true?
* It can be up to 255 characters long.
* It is limited to 63 characters plus the TLD.
* There is no limit to the length of a second-level domain.
* It must be exactly 10 characters long.

Answer 9

It is limited to 63 characters plus the TLD.

Explanation: A second-level domain (SLD) is limited to 63 characters. The SLD is the part of the domain name that comes directly before the top-level domain (TLD), such as ‘website’ in ‘website.com’. The SLD can include letters (a-z), numbers (0-9), and hyphens, but cannot start or end with a hyphen or contain consecutive hyphens.

Question 10

What is the maximum number of characters allowed in a full domain name, including all levels and the TLD?
* 63 characters
* 255 characters
* 253 characters
* No limit

Answer 10

253 characters

Explanation: The maximum length of a full domain name, including all subdomains, the second-level domain, and the top-level domain, is limited to 253 characters in the DNS system. This includes all characters and dots separating the different levels of the domain.

Question 11

What is a gTLD in the context of domain names?
* A global top-level domain used by international organizations
* A generic top-level domain such as .com or .org
* A government top-level domain reserved for government entities
* A geographic top-level domain representing a country code

Answer 11

A generic top-level domain such as .com or .org

Explanation: A gTLD, or generic top-level domain, is a category of TLDs that includes familiar extensions such as .com, .org, .net, and .edu. gTLDs were originally intended to represent the general category of the domain’s content, but with the expansion of the domain name system, they now include a wide variety of options beyond the original few.

Question 12

What does an ‘A’ record in DNS typically specify?
* The email servers for a domain
* The IPv6 address of a domain
* The IPv4 address of a domain
* A text description of the domain

Answer 12

The IPv4 address of a domain

Explanation: An ‘A’ record, or Address Record, is used in DNS to map a domain name to its corresponding IPv4 address, which is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication.

Question 13

What is the function of an ‘AAAA’ record in DNS settings?
* It points to an IPv4 address.
* It indicates the authorized email servers for a domain.
* It provides a text entry related to the domain.
* It points to an IPv6 address.

Answer 13

It points to an IPv6 address

Explanation: An ‘AAAA’ record is a DNS record that maps a domain name to its corresponding IPv6 address, which is the most recent version of Internet Protocol addresses, providing a much larger pool of addresses than IPv4.

Question 14

For what purpose is a ‘CNAME’ record used in the DNS?
* To specify IPv4 address for a domain
* To alias one domain name to another
* To list the email servers for a domain
* To provide a text field for domain-related information

Answer 14

To alias one domain name to another

Explanation: A ‘CNAME’ record, or Canonical Name record, is used in DNS to alias one domain name to another domain name. It is typically used when multiple domain names should resolve to the same IP address.

Question 15

What does an ‘MX’ record in DNS define?
* The canonical name for an alias
* The IPv6 address for the domain
* The servers that handle email for a domain
* A free text field for any text-based data

Answer 15

The servers that handle email for a domain

Explanation: An ‘MX’ record, or Mail Exchange record, specifies the mail server responsible for accepting email messages on behalf of a domain name. It can also specify the priority order of mail servers for load balancing and redundancy.

Question 16

How are ‘TXT’ records used in DNS?
* To direct traffic to an IPv4 address
* To resolve domain names to IPv6 addresses
* To alias domains to another domain’s canonical name
* To store text-based information for various purposes

Answer 16

To store text-based information for various purposes

Explanation: ‘TXT’ records provide a versatile space in DNS for text-based information. They can be used for various purposes, such as verifying domain ownership, specifying email sender policies to combat spam, or providing other domain-related information in a text format.

Question 17

What is the role of a Recursive DNS Server?
* To store the DNS records for a particular domain name
* To redirect to the correct Top Level Domain Server based on the request
* To act as a backup server in case the primary server goes down
* To cache domain name requests and respond to queries

Answer 17

To cache domain name requests and respond to queries

Explanation: The Recursive DNS Server, often provided by an ISP or chosen by the user, caches recently queried domain names. When a request is made, it first checks its local cache before initiating a search for the DNS record if it’s not already stored. If found, it sends the information back to the client, ending the request process.

Question 18

What is the first step your computer takes when making a DNS request?
* It requests the Recursive DNS Server.
* It checks its local cache for the domain address.
* It contacts the Root DNS Server.
* It queries the Authoritative DNS Server.

Answer 18

It checks its local cache for the domain address.

Explanation: When a DNS request is made, the computer first checks its local DNS cache to determine if the domain name has been recently resolved. If the address is in the cache, it uses this information, bypassing further DNS queries.

Question 19

What is the function of the Root DNS Server in the DNS query process?
* It provides the final DNS record for the domain name.
* It acts as the local cache for the client’s computer.
* It redirects the query to the correct TLD server based on the domain requested.
* It caches the DNS response for future requests.

Answer 19

It redirects the query to the correct TLD server based on the domain requested.

Explanation: Root DNS Servers are a critical part of the DNS hierarchy, serving as the backbone of the DNS system. Their primary role is to direct the Recursive DNS Server to the appropriate Top-Level Domain (TLD) server for the domain being requested.

Question 20

How does the Authoritative DNS Server fit into the DNS lookup process?
* It caches the DNS request for the client.
* It acts as the first point of contact for a DNS lookup.
* It stores DNS records for a domain and provides the definitive responses to queries.
* It assigns TTL values to DNS records.

Answer 20

It stores DNS records for a domain and provides the definitive responses to queries.

Explanation: The Authoritative DNS Server is responsible for holding the DNS records of a specific domain. When queried, it provides the authoritative DNS response, which includes the requested record type (e.g., A, AAAA, CNAME, MX, TXT) for a domain.

Question 21

What is TTL in the context of DNS, and why is it important?
* It is the protocol used to encrypt DNS queries.
* It is the value that indicates how long a DNS record should be cached.
* It is the identifier for the Root DNS Server.
* It is the name given to the Recursive DNS Server provided by ISPs.

Answer 21

It is the value that indicates how long a DNS record should be cached.

Explanation: TTL, or Time To Live, is a value in DNS records that specifies the duration (in seconds) that the record should be stored in a cache. This helps in reducing the load on DNS servers and speeds up web browsing by temporarily storing recent lookups.