Transcript domain name system.

DOMAIN NAME SYSTEM.
THE INTERNET’S POSTAL SYSTEM.
“Intellectuals solve problems,
geniuses prevent them.”
Albert Einstein.
OBJECTIVES.
• Background info.
• How big is DNS?
• Components of DNS and how they interrelate.
• How does the DNS function?
• Legislations involved with DNS.
• Limitations of DNS.
• Conclusion.
DEFINITION.
• Distributed and dynamic database, that
provides mapping between IP addresses &
Hostnames. ”DNS best practice 2011”
http://www.port.ac.uk
http://72.92.62.123
BACKGROUND.
• How did DNS evolve?
• Before the INTERNET…..
ARPANET
Manual
NAFNET
host file
NSFNET
Update
INTERNET
BACKGROUND.
PUBLIC DOMAIN NETWORK GROWTH
1200000
1000000
800000
600000
PUBLIC DOMAIN
NETWORK GROWTH
400000
200000
0
1980
1990
2000
2010
HOW BIG IS THE DNS?
DNS HIERARCHICAL TREE STRUCTURE
DNS ROOT SERVERS = 13 in number
TOP-LEVEL DOMAIN NAME SERVERS. - .org,
.com, .uk, .net, .mil, .edu etc.
SECOND-LEVEL DOMAIN NAME SERVERS. – in
the 1000s locally administered.
DNS NAMING CONVENTION.
www.port.ac.uk
Top Level Domain Name:
Second Level Domain Name:
Fully Qualified Domain Name:
.uk
.ac.uk.
www.port.ac.uk.
DNS COMPONENTS.
• DNS SERVERS – Computers that specifically
Keep a database with
information about the Host Locations.
• BIND – Server software used to manage this
information.
• S.O.A – Server Of Authority, main DNS server
that actually stores the IP addresses
and Hostnames.
DNS COMPONENTS.
FORWARD LOOK-UP ZONES:
- IP addresses and FQDN.
- NS Records
- A Records
- MX Records
- AAAA .IPv6 Addresses
- CNames
REVERSE LOOK-UP ZONES:
- Resolve FQDN of known IP Addresses.
FUNCTIONS OF DNS.
- Resolve IP Addresses from known Hostnames.
- Resolving process begins from the local
adjacent DNS servers.
- Escalation up the DNS Hierarchical Structure
until the DNS query is resolved.
www.port.ac.uk
www.hotmail.com
Local DNS
DNS
Server
External DNS
DNS
Server
WHO REGULATES DNS?
• PUBLIC DOMAIN – ICANN – Internet
Corporation for Assigned Names & Numbers.
- Registration.
- Annual fee payment.
- Legal responsibility.
• PRIVATE DOMAIN – local DNS Administration.
DNS LIMITATIONS.
• Amplification – DNS storing corrupt
information hence exponentially redirecting
network traffic incorrectly. DoS attacks.
• Global Control – Using DNS to control or filter
network traffic to promote ulterior motives.
i.e. Political Agendas, Propaganda etc.
• Economical Exploitation – Using DNS to cash
in hence attracting illegal activities i.e. Cyber
crime. E.g. Island of Tivalu sold their Domain
name `.tv’ in 2000 under a lot of controversy.
CONCLUSION.
• FUTURE DEVELOPMENT – ICANN introducing
gTLD (Generic Top-Level Domain Names).
• Concept of Brand Names - .apple, .google,
.microsoft, .ebay
• Advantages:
- Flexibility
- Intrinsic control.
- Brand recognition.
- Extended language support
REFERENCES:
• About.com. Wireless/Networking. Internet Protocol Tutorial – DNS.
2011.
http://compnetworking.about.com/od/internetaccessbestuses/l/aa02
0503a.htm
• Cisco Security Intelligence Operations. DNS Best Practices, Network
protection and Attack Identification. 2011. Retrieved from
http://www.cisco.com/web/about/security/intelligence/dnsbcp.html#3
• ICANN. Domain Name Structure and Delegation. RFC 1591. March
1994. http://tools.ietf.org/html/rfc1591
• Meyers M. 2007. ComptiA Network+ Guide to Managing and
Troubleshooting Networks. London. McGraw Hill.
• New generic Top-Level Domains. ICANN – 2011.
http://newgtlds.icann.org/
• Shane Kerr. 2010. BIND 10 in 10 Minutes.(PDF) Retrieved from
http://www.brussels38.icann.org/meetings/brussels2010/presentatio
n-ccnso-tech-day-bind-kerr-21jun10-en.pdf - 2011-06-28