DNS

Question 1

Domain Name System (DNS)

Answer 1

A global hierarchy of distributed name server databases that contain information on domains and hosts within those domains.

Question 2

Top-level domains (TLDs)

Answer 2

*Generic (.com, .org, .net, .info, .biz),
*Sponsored (.gov, .edu),
*Country code (.uk, .ca, .de).

Question 3

Who operates/manages top-level domains?

Answer 3

DNS is operated by ICANN (icann.org), which also manages the generic TLDs.

Country codes are generally managed by an organization appointed by the relevant government.

Question 4

Recursive Lookup

Answer 4

DNS query type whereby a server submits additional queries to other servers to obtain the requested information.

The queried server is not authoritative,

Question 5

Iterative Lookups

Answer 5

DNS query type whereby a server responds with information from its own data store only.

Responds to a query with either the requested record or the address of a name server at a lower level in the hierarchy that is authoritative for the namespace.

Question 6

Start of Authority (SOA) Record

Answer 6

Identifies the primary authoritative name server that maintains complete resource records for the zone.

Question 7

Name Server (NS) Record

Answer 7

Identify authoritative DNS name servers for the zone.

Question 8

Canonical Name (CNAME) Record

Answer 8

(or alias) record is used to configure an alias for an existing address record (A or AAAA).

Question 9

Mail Exchange (MX) Record

Answer 9

Identify an email server for the domain.

Question 10

Service (SRV) Record

Answer 10

Contains the service name and port on which a particular application is hosted.

Question 11

TXT Record

Answer 11

Store any free-form text that may be needed to support other network services.

Question 12

Pointer (PTR) Record

Answer 12

Maps an IP address to host name (reverse DNS query)

Question 13

Reverse DNS query

Answer 13

Resolve an IP address to a host name.

Question 14

Forward lookup zone

Answer 14

Returns an IP address (typical DNS query)

Question 15

Reverse lookup zone

Answer 15

Returns a hostname from a PTR record (reverse Query)

Question 16

Port DNS runs on

Answer 16

TCP/UDP 53

Question 17

Primary DNS Server

Answer 17

Zone records held on the server are editable

Question 18

Secondary DNS Server

Answer 18

*Holds a read-only copy of the zone.
*Maintained through a process of replication known as a zone transfer from a primary name server

Question 19

Zone Transfer

Answer 19

Mechanism by which a secondary name server obtains a read-only copy of zone records from the primary server.

Question 20

Authoritative Server

Answer 20

*Holds complete records for a domain
*Both primary and secondary name servers are authoritative.

Question 21

Cache-only Servers

Answer 21

*Don’t maintain a zone (primary or secondary)

Question 22

nut.widget.com

hostname = nut
domain suffix = widget.com
top level domain = .com

Answer 22

nut.widget.com

nut = hostname
widget.com = domain suffix
.com = top level domain

Question 23

DNSSEC

Answer 23

Uses encrypted digital signatures when passing DNS information between servers to help protect it from poisoning.

Question 24

DNS Record PTR

Answer 24

Pointer
Correlates an IP address with a domain name
Reverse DNS lookup

Question 25

Nameserver
Indicates which DNS nameserver has the authority

Answer 25

DNS Record NS

Question 26

Internal DNS

Answer 26

Allows cloud instances on the same network access each other using internal DNS names.

Question 27

DNS Latency

Answer 27

Time and delay that occurs whenever users request a particular domain name