This document provides an overview of the Domain Name System (DNS) including:
- The DNS uses a globally distributed database to translate human-friendly domain names to computer-friendly IP addresses.
- It has a hierarchical structure with top-level domains like .com and country codes delegated to different name servers, and subdomains can be further delegated.
- DNS name servers store records about their portion of the name space and resolve queries by either responding with records from their cache or by recursively querying other name servers until the answer is found.
The Domain Name System (DNS) is a hierarchical decentralized naming system that resolves Name to IP or vise versa.
DNS works with port no 53 (TCP and UDP )
For query resolving UDP protocol is used and for Zone transfer TCP port is used.
The Domain Name System (DNS) is a hierarchical decentralized naming system that resolves Name to IP or vise versa.
DNS works with port no 53 (TCP and UDP )
For query resolving UDP protocol is used and for Zone transfer TCP port is used.
Overview of the Domain Name System (DNS).
In the early days of the Internet, hosts had a fixed IP address.
Reaching a host required to know its numeric IP address.
With the growing number of hosts this scheme became quickly awkward and difficult to use.
DNS was introduced to give hosts human readable names that would be translated into a numeric IP addresses on the fly when a requesting host tried to reach another host.
To facilitate a distributed administration of the domain names, a hierarchic scheme was introduced where responsibility to manage domain names is delegated to organizations which can further delegate management of sub-domains.
Due to its importance in the operation of the Internet, domain name servers are usually operated redundantly. The databases of both servers are periodically synchronized.
This Presentation explains about Domain Name System Records and Their Usage.
This explains DNS Records to New Beginners in an accurate manner. Get to learn live technology in an enhanced way only at Hackveda
Please note that you may not find detailed description on many things since the seminar was meant to be delivered orally and the slides were just meant to be a visual device. Enjoy!
Overview of the Domain Name System (DNS).
In the early days of the Internet, hosts had a fixed IP address.
Reaching a host required to know its numeric IP address.
With the growing number of hosts this scheme became quickly awkward and difficult to use.
DNS was introduced to give hosts human readable names that would be translated into a numeric IP addresses on the fly when a requesting host tried to reach another host.
To facilitate a distributed administration of the domain names, a hierarchic scheme was introduced where responsibility to manage domain names is delegated to organizations which can further delegate management of sub-domains.
Due to its importance in the operation of the Internet, domain name servers are usually operated redundantly. The databases of both servers are periodically synchronized.
This Presentation explains about Domain Name System Records and Their Usage.
This explains DNS Records to New Beginners in an accurate manner. Get to learn live technology in an enhanced way only at Hackveda
Please note that you may not find detailed description on many things since the seminar was meant to be delivered orally and the slides were just meant to be a visual device. Enjoy!
DNS, which stands for domain name system, controls your domain name's website and email settings. When visitors go to your domain name, its DNS settings control which company's server it reaches out to.
The Domain Name System (DNS) is a critical part of Internet infrastructure and the largest distributed Internet directory service. DNS translates names to IP addresses, a required process for web navigation, email delivery, and other Internet functions. However, the DNS infrastructure is not secure enough unless the security mechanisms such as Transaction Signatures (TSIG) and DNS Security Extensions (DNSSEC) are implemented. To guarantee the availability and the secure Internet services, it is important for networking professionals to understand DNS concepts, DNS Security, configurations, and operations.
This course will discuss the concept of DNS Operations in detail, mechanisms to authenticate the communication between DNS Servers, mechanisms to establish authenticity, and integrity of DNS data and mechanisms to delegate trust to public keys of third parties. Participant will be involved in Lab exercises and do configurations based on number of scenarios.
The Domain Name System (DNS) provides a way to map or translate an unfriendly numerical IP address into a people-friendly format. Although this translation isn’t mandatory, it does make the network much more useful and easy to work with for humans.
Computer Networks Module 1 - part 2.pdfShanthalaKV
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DNS; The Internet's Directory Service: Services Provided by DNS, Overview of How DNS Works, DNS Records and Messages, Peer-to-Peer Applications: P2P File Distribution, Distributed Hash Tables, Socket Programming: creating Network Applications: Socket Programming with UDP, Socket Programming with TCP.
The application layer sits at Layer 7, the top of the Open Systems Interconnection (OSI) communications model. It ensures an application can effectively communicate with other applications on different computer systems and networks. The application layer is not an application.
This 7-second Brain Wave Ritual Attracts Money To You.!nirahealhty
Discover the power of a simple 7-second brain wave ritual that can attract wealth and abundance into your life. By tapping into specific brain frequencies, this technique helps you manifest financial success effortlessly. Ready to transform your financial future? Try this powerful ritual and start attracting money today!
APNIC Foundation, presented by Ellisha Heppner at the PNG DNS Forum 2024APNIC
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Bridging the Digital Gap Brad Spiegel Macon, GA Initiative.pptxBrad Spiegel Macon GA
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Meet up Milano 14 _ Axpo Italia_ Migration from Mule3 (On-prem) to.pdfFlorence Consulting
Quattordicesimo Meetup di Milano, tenutosi a Milano il 23 Maggio 2024 dalle ore 17:00 alle ore 18:30 in presenza e da remoto.
Abbiamo parlato di come Axpo Italia S.p.A. ha ridotto il technical debt migrando le proprie APIs da Mule 3.9 a Mule 4.4 passando anche da on-premises a CloudHub 1.0.
1.Wireless Communication System_Wireless communication is a broad term that i...JeyaPerumal1
Wireless communication involves the transmission of information over a distance without the help of wires, cables or any other forms of electrical conductors.
Wireless communication is a broad term that incorporates all procedures and forms of connecting and communicating between two or more devices using a wireless signal through wireless communication technologies and devices.
Features of Wireless Communication
The evolution of wireless technology has brought many advancements with its effective features.
The transmitted distance can be anywhere between a few meters (for example, a television's remote control) and thousands of kilometers (for example, radio communication).
Wireless communication can be used for cellular telephony, wireless access to the internet, wireless home networking, and so on.
2. Overview
• Introduction to the DNS
• DNS Components
• DNS Structure and Hierarchy
• The DNS in Context
3. DNS History (1)
• ARPANET utilized a central file HOSTS.TXT
– Contains names to addresses mapping
– Maintained by SRI’s NIC (Stanford-Research-
Institute: Network-Information-Center)
• Administrators email changes to NIC
– NIC updates HOSTS.TXT periodically
• Administrators FTP (download) HOSTS.TXT
4. DNS History (2)
• As the system grew, HOSTS.TXT had
problems with:
– Scalability (traffic and load)
– Name collisions
– Consistency
• In 1984, Paul Mockapetris released the first
version (RFCs 882 and 883, superseded by
1034 and 1035 …)
5. The DNS is…
• The “Domain Name System”
• What Internet users use to reference
anything by name on the Internet
• The mechanism by which Internet software
translates names to attributes such as
addresses
6. The DNS is also…
• A globally distributed, scalable, reliable database
• Comprised of three components
– A “name space”
– Servers making that name space available
– Resolvers (clients) which query the servers about the
name space
7. DNS as a Lookup Mechanism
• Users generally prefer names to numbers
• Computers prefer numbers to names
• DNS provides the mapping between the two
– I have “x”, give me “y”
8. DNS as a Database
• Keys to the database are “domain names”
– www.foo.com, 18.in-addr.arpa, 6.4.e164.arpa
• Over 200,000,000 domain names stored
• Each domain name contains one or more
attributes
– Known as “resource records”
• Each attribute individually retrievable
9. Global Distribution
• Data is maintained locally, but retrievable
globally
– No single computer has all DNS data
• DNS lookups can be performed by any
device
• Remote DNS data is locally cachable to
improve performance
10. Loose Coherency
• Each version of a subset of the database (a zone)
has a serial number
– The serial number is incremented on each database change
• Changes to the master copy of the database are
propagated to replicas according to timing set by
the zone administrator
• Cached data expires according to timeout set by
zone administrator
11. Scalability
• No limit to the size of the database
• No limit to the number of queries
– Tens of thousands of queries handled easily
every second
• Queries distributed among masters, slaves,
and caches
12. Reliability
• Data is replicated
– Data from master is copied to multiple slaves
• Clients can query
– Master server
– Any of the copies at slave servers
• Clients will typically query local caches
• DNS protocols can use either UDP or TCP
– If UDP, DNS protocol handles retransmission,
sequencing, etc.
13. Dynamicity
• Database can be updated dynamically
– Add/delete/modify of any record
– Only master can be dynamically updated
• Modification of the master database triggers
replication
14. Overview
• Introduction to the DNS
• DNS Components
– The name space
– The servers
– The resolvers
• DNS Structure and Hierarchy
• The DNS in Context
15. The Name Space
• The name space is the structure of the DNS database
– An inverted tree with the root node at the top
• Each node has a label
– The root node has a null label, written as “”
t o p - l e v e l n o d e
s e c o n d - le v e l n o d e s e c o n d - le v e l n o d e
t h i r d - l e v e l n o d e
t o p - l e v e l n o d e
s e c o n d - l e v e l n o d e
s e c o n d - l e v e l n o d e s e c o n d - l e v e l n o d e
t h i r d - l e v e l n o d e t h i r d - l e v e l n o d e
t o p - le v e l n o d e
T h e r o o t n o d e
" "
17. to p -1
fo o fo o
to p -2
fo o a t& t
to p -3
b a r b a z
" "
Labels
• Each node in the tree must have a
label
– A string of up to 63 bytes
– RFCs 852 and 1123 define legal
characters for “hostnames”
• A-Z, 0-9, and “-” only with a-z
and A-Z treated as the same
• Sibling nodes must have unique
labels
• The null label is reserved for the
root node
18. Domain Names
• A domain name is the sequence of labels from a node to the root,
separated by dots (“.”s), read left to right
– The name space has a maximum depth of 127 levels
– Domain names are limited to 255 characters in length
• A node’s domain name identifies its position in the name space
w e s t
d a k o t a
n o m i n u m m e t a i n f o
e a s t w w w
t o r n a d o
c o m
e d u g o v
b e r k e l e y n w u
in t
n a t o
m i l
a r m y
n e t o r g
u u
" "
19. Subdomains
• One domain is a subdomain of another if its
domain name ends in the other’s domain name
– So sales.nominum.com is a subdomain of
• nominum.com & com
– nominum.com is a subdomain of com
20. Delegation
• Administrators can create subdomains to group hosts
– According to geography, organizational affiliation etc.
• An administrator of a domain can delegate responsibility
for managing a subdomain to someone else
• The parent domain retains links to the delegated
subdomains
21. Delegation Creates Zones
• Each time an administrator delegates a subdomain,
a new unit of administration is created
– The subdomain and its parent domain can now be
administered independently
– These units are called zones
– The boundary between zones is a point of delegation in
the name space
• Delegation is good: it is the key to scalability
22. Dividing a Domain into Zones
nominum.com
domain
nominum.com
zone
ams.nominum.com
. c o m . e d u
rwc.nominum.com zone
zone
. a r p a
a c m e b w
n o m i n u m n e t s o l
r w c w w w f t p
m o l o k a i s k y e
a m s
g o u d a c h e d d a r
" "
23. Overview
• Introduction to the DNS
• DNS Components
– The name space
– The servers
– The resolvers
• DNS Structure and Hierarchy
• The DNS in Context
24. Name Servers
• Name servers store information about the name
space in units called “zones”
– The name servers that load a complete zone are said to
“have authority for” or “be authoritative for” the zone
• Usually, more than one name server are
authoritative for the same zone
– This ensures redundancy and spreads the load
• Also, a single name server may be authoritative
for many zones
25. Name Servers and Zones
128.8.10.5 serves Name Servers
Zones
data for both
nominum.com
and isc.org zones
128.8.10.5
nominum.com
202.12.28.129
204.152.187.11
isc.org
202.12.28.129
serves data for
nominum.com
zone only
204.152.187.11
serves data for
isc.org zone only
26. Types of Name Servers
• Two main types of servers
– Authoritative – maintains the data
• Master – where the data is edited
• Slave – where data is replicated to
– Caching – stores data obtained from an authoritative
server
• No special hardware necessary
27. Name Server Architecture
• You can think of a name server as part of:
– database server, answering queries about the
parts of the name space it knows about (i.e., is
authoritative for),
– cache, temporarily storing data it learns from
other name servers, and
– agent, helping resolvers and other name servers
find data
28. Name Server Architecture
Master
Zone
data
file
Zone transfer server
From
disk
Name Server Process
Authoritative Data
(primary master and
slave zones)
Cache Data
(responses from
other name servers)
Agent
(looks up queries
on behalf of resolvers)
29. Authoritative Data
Resolver
Response
Query
Name Server Process
Authoritative Data
(primary master and
slave zones)
Cache Data
(responses from
other name servers)
Agent
(looks up queries
on behalf of resolvers)
30. Using Other Name Servers
Another
name
server
Response
Resolver
Query
Query
Name Server Process
Authoritative Data
(primary master and
slave zones)
Cache Data
(responses from
other name servers)
Agent
(looks up queries
on behalf of resolvers)
Response
31. Cached Data
Response
Query
Name Server Process
Authoritative Data
(primary master and
slave zones)
Cache Data
(responses from
other name servers)
Agent
(looks up queries
on behalf of resolvers)
Resolver
32. Overview
• Introduction to the DNS
• DNS Components
– The name space
– The servers
– The resolvers
• DNS Structure and Hierarchy
• The DNS in Context
33. Name Resolution
• Name resolution is the process by which resolvers
and name servers cooperate to find data in the
name space
• Closure mechanism for DNS?
– Starting point: the names and IP addresses of the name
servers for the root zone (the “root name servers”)
– The root name servers know about the top-level zones
and can tell name servers whom to contact for all TLDs
34. Name Resolution
• A DNS query has three parameters:
– A domain name (e.g., www.nominum.com),
• Remember, every node has a domain name!
– A class (e.g., IN), and
– A type (e.g., A)
– http://network-tools.com/nslook/
• Upon receiving a query from a resolver, a name
server
– 1) looks for the answer in its authoritative data and its
cache
– 2) If step 1 fails, the answer must be looked up
35. The Resolution Process
• Let’s look at the resolution process step-by-step:
annie.west.sprockets.com
ping www.nominum.com.
36. The Resolution Process
• The workstation annie asks its configured name
server, dakota, for www.nominum.com’s address
dakota.west.sprockets.com
What’s the IP address
of
www.nominum.com?
annie.west.sprockets.com
ping www.nominum.com.
37. The Resolution Process
• The name server dakota asks a root name server, m, for
www.nominum.com’s address
annie.west.sprockets.com
ping www.nominum.com.
m.root-servers.net
dakota.west.sprockets.com
What’s the IP address
of
www.nominum.com?
38. The Resolution Process
• The root server m refers dakota to the com name servers
• This type of response is called a “referral”
annie.west.sprockets.com
ping www.nominum.com.
m.root-servers.net
dakota.west.sprockets.com Here’s a list of the
com name servers.
Ask one of them.
39. The Resolution Process
• The name server dakota asks a com name server, f,
for www.nominum.com’s address
annie.west.sprockets.com
What’s the IP address
ping www.nominum.com.
m.root-servers.net
dakota.west.sprockets.com
of
www.nominum.com?
f.gtld-servers.net
40. The Resolution Process
• The com name server f refers dakota to the
nominum.com name servers
annie.west.sprockets.com
ping www.nominum.com.
m.root-servers.net
f.gtld-servers.net
dakota.west.sprockets.com
Here’s a list of the
nominum.com
name servers.
Ask one of them.
41. The Resolution Process
• The name server dakota asks a nominum.com name server,
ns1.sanjose, for www.nominum.com’s address
annie.west.sprockets.com
What’s the IP address
of
www.nominum.com?
ping www.nominum.com.
m.root-servers.net
f.gtld-servers.net
dakota.west.sprockets.com
ns1.sanjose.nominum.net
42. The Resolution Process
• The nominum.com name server ns1.sanjose
responds with www.nominum.com’s address
annie.west.sprockets.com
ping www.nominum.com.
m.root-servers.net
f.gtld-servers.net
dakota.west.sprockets.com
Here’s the IP ns1.sanjose.nominum.net
address for
www.nominum.com
43. The Resolution Process
• The name server dakota responds to annie with
www.nominum.com’s address
Here’s the IP
address for
www.nominum.com
annie.west.sprockets.com
ping www.nominum.com.
m.root-servers.net
f.gtld-servers.net
dakota.west.sprockets.com
ns1.sanjose.nominum.net
44. Resolution Process (Caching)
• After the previous query, the name server dakota now knows:
– The names and IP addresses of the com name servers
– The names and IP addresses of the nominum.com name servers
– The IP address of www.nominum.com
• Let’s look at the resolution process again
annie.west.sprockets.com
ping ftp.nominum.com.
45. Resolution Process (Caching)
• The workstation annie asks its configured name
server, dakota, for ftp.nominum.com’s address
What’s the IP address
of ftp.nominum.com?
annie.west.sprockets.com
ping ftp.nominum.com.
m.root-servers.net
f.gtld-servers.net
dakota.west.sprockets.com
ns1.sanjose.nominum.net
46. Resolution Process (Caching)
• dakota has cached a NS record indicating ns1.sanjose is an
nominum.com name server, so it asks it for
ftp.nominum.com’s address
What’s the IP address
of ftp.nominum.com?
annie.west.sprockets.com
ping ftp.nominum.com.
m.root-servers.net
f.gtld-servers.net
dakota.west.sprockets.com
ns1.sanjose.nominum.net
47. Resolution Process (Caching)
• The nominum.com name server ns1.sanjose
responds with ftp.nominum.com’s address
Here’s the IP
address for
ftp.nominum.com
annie.west.sprockets.com
ping ftp.nominum.com.
m.root-servers.net
f.gtld-servers.net
dakota.west.sprockets.com
ns1.sanjose.nominum.net
48. Resolution Process (Caching)
• The name server dakota responds to annie with
ftp.nominum.com’s address
Here’s the IP
address for
ftp.nominum.com
annie.west.sprockets.com
ping ftp.nominum.com.
m.root-servers.net
f.gtld-servers.net
dakota.west.sprockets.com
ns1.sanjose.nominum.net
51. Recursive Name Resolution (2)
Server for
node
Should
resolve Looks up Passes to
child
Receives
and caches
Returns to
requester
cs <ftp> #<ftp> -- -- #<ftp>
vu <cs,ftp> #<cs> <ftp> #<ftp> #<cs>
#<cs, ftp>
ni <vu,cs,ftp> #<vu> <cs,ftp> #<cs>
#<cs,ftp>
#<vu>
#<vu,cs>
#<vu,cs,ftp>
root <ni,vu,cs,ftp> #<nl> <vu,cs,ftp> #<vu>
#<vu,cs>
#<vu,cs,ftp>
#<nl>
#<nl,vu>
#<nl,vu,cs>
#<nl,vu,cs,ftp>
• Recursive name resolution of <nl, vu, cs, ftp>. Name
servers cache intermediate results for subsequent
lookups.
52. Iterative versus Recursive
Resolution (1)
Performance-WHohwic hab woourt kcso wbmiesmteteu, rnw wihciaitcthiho cnias c cbhoeistntt?ger??
53. Iterative versus Recursive
Resolution (2)
• Performance-wise, which is better?
– Recursive method puts higher performance demand
on each name server
• Which works better with caching?
– Recursive method works better with caching
• How about communication cost?
– Recursive method can reduce communication cost
54. Iterative versus Recursive
Resolution (3)
• The comparison between recursive and iterative name
resolution with respect to communication costs.
55. Overview
• Introduction to the DNS
• DNS Components
• DNS Structure and Hierarchy
• The DNS in Context
56. DNS Structure and Hierarchy
• The DNS imposes no constraints on how the DNS
hierarchy is implemented except:
– A single root
– The label restrictions
– So, can we create a host with a name a.wonderful.world?
• If a site is not connected to the Internet, it can use any
domain hierarchy it chooses
– Can make up whatever TLDs (top level domains) you want
• Connecting to the Internet implies use of the existing
DNS hierarchy
57. Top-level Domain (TLD) Structure
• In 1983 (RFC 881), the idea was to have TLDs correspond
to network service providers
– e.g., ARPA, DDN, CSNET, etc.
• Bad idea: if your network changes, your name changes
• By 1984 (RFC 920), functional domains was established
– e.g., GOV for Government, COM for commercial, EDU for
education, etc.
• RFC 920 also
– Provided country domains
– Provided “Multiorganizations”
• Large, composed of other (particularly international) organizations
– Provided a stable TLD structure until 1996 or so
58. The Current TLDs
G e n e r i c T L D s
( g T L D s )
C O M
C o m m e r c ia l O r g a n iz a t io n s
N E T
N e t w o r k I n f r a s t r u c t u r e
O R G
O t h e r O r g a n i z a t i o n s
C o u n t r y C o d e T L D s
A F
( c c T L D s )
A f g h a n i s t a n
A L
A l b a n ia
D Z
A l g e r ia
. . .
Y U
Y u g o s la v ia
Z M
Z a m b ia
Z W
Z i m b a b w e
I n t e r n a t i o n a l T L D s
( iT L D s )
I N T
I n t e r n a t io n a l T r e a t y O r g a n i z a t i o n s
A R P A
( T r a n s i t i o n D e v i c e )
U S L e g a c y T L D s
( u s T L D s )
G O V
G o v e r n m e n t a l O r g a n iz a t i o n s
M I L
M i l it a r y O r g a n iz a t io n s
E D U
E d u c a t io n a l I n s t i t u t i o n s
" . "
59. Internet Corporation for Assigned
Names and Numbers (ICANN)
• ICANN’s role: to oversee the management of
Internet resources including
– Addresses
• Delegating blocks of addresses to the regional registries
– Protocol identifiers and parameters
• Allocating port numbers, etc.
– Names
• Administration of the root zone file
• Oversee the operation of the root name servers
60. The Root Nameservers
• The root zone file lists the names and IP addresses
of the authoritative DNS servers for all top-level
domains (TLDs)
• The root zone file is published on 13 servers, “A”
through “M”, around the Internet
• Root name server operations currently provided
by volunteer efforts by a very diverse set of
organizations
61. Root Name Server Operators
Nameserver Operated by:
A Verisign (US East Coast)
B University of S. California –Information Sciences Institute (US West Coast)
C Cogent Communications (US East Coast)
D University of Maryland (US East Coast)
E NASA (Ames) (US West Coast)
F Internet Software Consortium (US West Coast)
G U. S. Dept. of Defense (ARL) (US East Coast)
H U. S. Dept. of Defense (DISA) (US East Coast)
I Autonomica (SE)
J Verisign (US East Coast)
K RIPE-NCC (UK)
L ICANN (US West Coast)
M WIDE (JP)
62. Registries, Registrars, and Registrants
• A classification of roles in the operation of a domain name space
• Registry
– the name space’s database
– the organization which has edit control of that database
– the organization which runs the authoritative name servers for that
name space
• Registrar
– the agent which submits change requests to the registry on behalf of
the registrant
• Registrant
– the entity which makes use of the domain name
63. Registries, Registrars, and Registrants
Registry Zone DB
Registrar submits
add/modify/delete
to registry
Registrar Registrar Registrar
End user requests
add/modify/delete
RReeggiissttrraannttss
Master
updated
Registry updates
zone
Slaves
updated
64. Verisign: the registry and
registrar for gTLDs
• .COM, .NET, and .ORG
– By far the largest top level domains on the Internet
today
• Verisign received the contract for the registry
for .COM, .NET, and .ORG
– also a registrar for these TLDs
66. Load Concerns
• DNS can handle the load
– DNS root servers get approximately 3000
queries per second
• Empirical proofs (DDoS attacks) show root name
servers can handle 50,000 queries per second
– Limitation is network bandwidth, not the DNS protocol
– in-addr.arpa zone, which translates numbers to
names, gets about 2000 queries per second
67.
68. Performance Concerns
• DNS is a very lightweight protocol
– Simple query – response
• Any performance limitations are the result
of network limitations
– Speed of light
– Network congestion
– Switching/forwarding latencies
69. Security Concerns
• Base DNS protocol (RFC 1034, 1035) is insecure
– DNS spoofing (cache poisoning) attacks are possible
• DNS Security Enhancements (DNSSEC, RFC
2565) remedies this flaw
– But creates new ones
• DoS attacks
• Amplification attacks
• DNSSEC strongly discourages large flat zones
– Hierarchy (delegation) is good
Editor's Notes
Advanced Research Projects Agency Network (ARPANET) was the world&apos;s first operational packet switching network, the first network to implement TCP/IP
RFC: Request for Comments
RFC 882 - Domain names: Concepts and facilities
ITU: International Telecommunication Union
1: US/CA
81: JP
BIND: Berkeley Internet Name Domain
Also, the caching resolver can insert data into the cache, and can &quot;query&quot; the cache and the database server.
ARPA: Advanced Research Projects Agency
ARPA: originally was the acronym for the Advanced Research Projects Agency (ARPA), the funding organization in the United States that developed the precursor of the Internet (ARPANET),
it now stands for Address and Routing Parameter Area.
Root zone file lists the names and numeric IP addresses of the authoritative DNS servers for all top-level domains (TLDs)
a spoofing attack is a situation in which one person or program successfully masquerades as another by falsifying data