The document provides a brief history of the Internet and an overview of the Domain Name System (DNS). It discusses the development of early packet networks like ARPANET and the invention of TCP/IP. It also describes the roles of organizations like ICANN and ARIN in managing domain names, IP addresses, and other Internet resources. Finally, it explains the basic functioning of DNS through record types like A, MX, NS, and PTR that map domain names to IP addresses and vice versa.

1. Brief Internet History &
DNS (Domain Name
System)
Bill Miller

2. Short History of the Internet
-- Packet switching as opposed to circuit
switching. Designed to avoid any failures.
○ ARPANET -- Advanced Research Projects Agency
Network -- the 1st packet switching (or store and
foward) network (DARPA work) (split
DDD/MILNET in 80's)
i. internet precursor
a. AlohaNet -- First wireless packet network
ii. Used packet radios, and led to CSMA leading to
ethernet by Robert Metcalf (Xerox Parc-> 3com)
iii. precursor to 1G+ mobile channels... for GPRS
and SMS, AX.25 (amature X.25 -- packet
switched WAN non ISO, non TCP/IP)
●

3. Some the real inventors
(Gore) A
● Vint Cerf
○ TCP/IP (co-inventor) / program manager of DARPA
○ Moved to MCI (email), key figure in setting up
ICANN (Internet Corporation for Assigned Numbers
and Names), Internet Society, ...
● Bob Kahn
○ TCP/IP (co-inventor)
○ BBN and first IMPs (interface Message Processor) ,
(ran ARAPNET routers), ...
● Leonard Klienrock
○ UCLA prof. -- queiueng theory (packet networks)
○ Supervized first ARPANET connection at UCLA - '69
○ IMP build out and usage
●

4. Some the real inventors
(Gore)
● John Postel
○ RFC's (Request For Commments) editor
■ intially idea flesh out for ARPANET or any
DARPA research
■ now memoradim of ITEF , sometimes standard
○ coordinated IANA (Internet Assigned Numbers
Authority)
○ Setup NIC (Network Information Center) with SRI
(Standford Research Institute)
■ 1st DNS authority was the NIC
■ Requested current DNS -- wrote by Paul
Mockepetris in 1983

5. Some the real inventors
(Gore)
● Paul Vixie
○ BIND and Cron -- author of current versions
■ BIND - from UCB unix, Berkely Internet Name
Domain
○ Founder of ISC -- Internet Systems Consortium
(BIND, DHCP, internet survey report (ML), ...)
○ co-inventor maintainer of MAPS (Mail Abuse
Prevention System)
■ 1st email spam blocking lists built on DNS
○ ARIN board member
○ Security/Stability member for ICANN

6. Internet Growth and Size

7. Todays Organizations
● ICANN - Internet Corporation for Assigned
Names and Numbers
a. Coordination of internet unique identifiers
(Domains, IPs, ASNs, ...)
b. SRI's NIC-->NSI --> ICANN(IANA) / (NSI->
Verisign) / ARIN
c. Approves registries and registrars (EPP,DNS,whois)
d. Oversee TLDs, root DNS servers (13), IP assignment,
ASN(s) (for BGP between seperate networks)
e. gTLD and ccTLD, and ...New generic TLD(s) .... a
new era...
i. current TLDs http:// www.iana.
org/domains/root/db
●

8. Todays Organizations
● ARIN - American Registry for Internet
Numbers
a. oversee IPs, ASNs, WHOIS, Reverse DNS
b. one of 5 RIR (Regional Internet Registries)
● IANA - Internet Assigned Numbers
Authority
a. Ran by ICANN
i. manages DNS root servers and .int, .arpa
domains TLDs
ii. manages global IPs and ASNs to individual RIRs
like ARIN
iii. Protocol Assignments (which
sockets/ports/services)

9. DNS (Domain Name
System)
DNS
○ Map Names to IPs (forward map), and IPs to Names
(reverse mapping)
○ With Millions of servers(hosts), unreliable networks,
servers, no SPOFs -- how do we do it.
■ Delegation / Authorization
● hierarchical sctructure of data (zones) , any zone can be
Delegated. This is a Tree structure of data.
● Root Level Zones (historically gTLD & ccTLD...)
●
●

10. DNS (Domain Name
System)
DNS
● Authoritative DNS
○ each Domain must have authoritative HOST who is
the master in terms of lookups
■ Any level (or zone) can be delegated to another
host.
■ The top level is called the root level or zone ( each
TLD zone is delegated to a registrar (as defined
by ICANN for each gTLD, and to a country for
each ccTLD) see http:// www.iana.
org/domains/root/db
●

11. DNS (Domain Name
System)
● DNS port 53 (UDP 1st, TCP/Ip port failback)
● DNS DATA and RecordTypes
○ SOA - Start of Authority Record
name ttl class rr name-server email-addr (sn ref ret ex min)
example.com. IN SOA ns.example.com. hostmaster.example.com. (
2003080800 ; sn = serial number
172800 ; ref = refresh = 2d
900 ; ret = update retry = 15m
1209600 ; ex = expiry = 2w
3600 ; min = minimum = 1h
)
; the following are also valid using @ and blank
@ IN SOA ns.example.com. hostmaster.example.com. (
IN SOA ns.example.com. hostmaster.example.com. (
●
●

12. DNS (Domain Name
System)
● NS - Name Server
; zone file fragment for example.com
$TTL 2d ; zone TTL default = 2 days or 172800 seconds
$ORIGIN example.com.
@ IN SOA ns.example.com. hostmaster.example.com. (
2003080800 ; serial number
1d12h ; refresh = 1 day 12 hours
15M ; update retry = 15 minutes
3W12h ; expiry = 3 weeks + 12 hours
2h20M ; minimum = 2 hours + 20 minutes
)
IN NS ns.example.com.
IN NS ns.example.net.
...
; A record for ns.example.com. RR above
ns IN A 192.168.2.1
; the above could have been written as
; ns.example.com. IN A 192.168.2.1
; ns.example.net is out-of-zone (or out-of-bailiwick)
; an A RRs is not required (and will be rejected if present)
○ NS - Name Server
name ttl class rr name
example.com. IN NS ns1.example.com.
; the in-zone name server(s) have an A record
ns1 IN A 192.168.0.3
ns2 IN A 192.168.0.3
; name servers not in zone - no A records required
IN NS ns1.example.net.
IN NS ns1.example.org.
●
●

13. DNS (Domain Name
System)
● A - Address (IPv4)
; zone fragment for example.com
$TTL 2d ; zone default = 2 days or 172800 seconds
joe IN A 192.168.0.3 ; joe & www = same ip
www IN A 192.168.0.3
; functionally the same as the record above
www.example.com. A 192.168.0.3
fred 3600 IN A 192.168.0.4 ; ttl overrides $TTL default
ftp IN A 192.168.0.24 ; round robin with next
● AAA - Address (Ipv60
; zone fragment for example.com
$TTL 2d ; zone default = 2 days or 172800 seconds
$ORIGIN example.com.
....
joe IN AAAA 2001:db8::3 ; joe & www = same ip
www IN AAAA 2001:db8::3
; functionally the same as the record above
www.example.com. AAAA 2001:db8::3
fred 3600 IN AAAA 2001:db8::4 ; ttl =3600 overrides $TTL default
ftp IN AAAA 2001:db8::5 ; round robin with next
IN AAAA 2001:db8::6
mail IN AAAA 2001:db8::7 ; mail = round robin
mail IN AAAA 2001:db8::32
mail IN AAAA 2001:db8::33
●

14. DNS (Domain Name
System)
● MX - Mail eXchanger
name ttl class rr pref name
example.com. IN MX 10 mail.example.com.
IN MX 10 mail ; short form
; the line above is functionally the same as the line below
; example.com. IN MX 10 mail.example.com.
; any number of mail servers may be defined
IN MX 20 mail2.example.com.
; use an external back-up
IN MX 30 mail.example.net.
○ PTR - Pointer (reverse -- opposite of A record)
name ttl class rr name
15 IN PTR www.example.com.
$TTL 2d ; 172800 secs
$ORIGIN 23.168.192.IN-ADDR.ARPA.
; 2 below is actually an unqualified name and becomes
; 2.23.168.192.IN-ADDR.ARPA.
2 IN PTR joe.example.com. ; FDQN
....
15 IN PTR www.example.com.
....
$ORIGIN 0.0.0.0.8.b.d.0.1.0.0.2.IP6.ARPA.
; the second name servers is
; external to this zone (domain).
IN NS ns2.example.net.
; PTR RR maps a IPv6 address to a host name
; hosts in subnet ID 1
1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.1.0.0.0 IN PTR ns1.example.com.
●

15. DNS (Domain Name
System)
● CNAME - aliase or realname mapped to Canocial Name
$ORIGIN example.com.
....
server1 IN A 192.168.0.3
www IN CNAME server1
ftp IN CNAME server1
○ TXT - text
○ other special cases (
■ TTL on data, and via client server DNS software
■ DNS Caching (at client, at hosts, .... recursive in
nature)
■ Recursive lookups
■ DNS format types
●

16. DNS (Domain Name
System)
-- special cases
○ TXT - text
○ other special cases (
■ TTL on data, and via client server DNS software
■ DNS Caching (at client, at hosts, .... recursive in
nature)
■ Recursive lookups
■ TSEC, notify, txfr, ...
●
●

17. DNS (Domain Name
System)
DNS
●
■ DNS Caching (at client, at hosts, .... recursive in
nature)
■ Recursive lookups
●
●

18. Whois (DB lookups for
Domains / IPs /....)
● whois -- system for Domains and IPs
○ simple telnet TCP/IP for data using authoritative
server
● examples
○ whois webhero.com
○ whois billmiller.tel
○ whois 204.215.60.0
■ whois -h whois.arin.net NET-204-215-60-0-1

19. DNS config / tools
● DNS config (*nix)
○ /etc/resolv.conf -- specify DNS servers
○ /etc/nsswitch.conf -- order of DNS lookup (files,db,
DNS)
○ /etc/hosts -- flat file of hardcoded DNS lookups
● DNS Server S/w
○ BIND
○ djbdns / tinydns -- by D. J. Bernstien

20. DNS config / tools
● DNS Tools ( and live examples)
○ nslookup
○ host
bill$ host www.allplayers.com
www.allplayers.com has address 174.129.39.74
bill$ host 209.217.1.2
2.1.217.209.in-addr.arpa domain name pointer ns1.catalog.com.
○ dig
○ web-based ... (iptools.com, www.intodns.com, ...)