Load Balanced DNS Server

1
Load Balanced DNS Server

• A server which cycles through IP addresses when
• responding to requests for a particular host name
• Process
• A DNS client asks for the IP address for a
  particular
• host name.
• Our server goes to the next IP address on a list
  of
• IP addresses for web servers and returns it.
• The web servers are essentially the same and
  handle
• the clients http request.

2
Alternate Implementations of Load Balancing

• IP Spoofing
• Replace destination address on packets received
  by load balancer with IP address
• of web server you are sending to.
• - Let web servers respond directly to client.
• Data moving
• Load balancer receives and distributes packets to
  different web servers.
• Let web servers perform tasks and send response
  packets back through load balancer.

3
Advantages/Disadvantages

• IP Spoofing
• Need to work with raw sockets and alter packets.
  Very complicated.
• Advantage Allows for detailed distribution of
  packets.
• Data Moving
• Single point of failure.
• Bottleneck.

4
Implementation Process

• Decided on using DNS Load Balancing
• Made a DNS server which cycles through web
  servers to return to clients.
• Made a tester which makes a multitude of
  requests.
• Implemented adding and shutting down web servers

5
Massive DNS Client

• Sends many requests for the same host name to the
  DNS server.
• Requests a page from the address returned from
  the DNS server.
• Times how long to get the page and writes the
  time to a file.

6
DNS Server

• First add the web servers you would like to use
• When the DNS server receives a request for a
  host name it is load balancing it cycles through
  available web servers that have that host.

7
Protocol

• User tells web server IP address of DNS server it
  wants to be added to
• DNS server takes add message and adds web server
  to a hash table containing all of the web servers

8
What we learned

• Sockets and different types of input and output
  streams
• HTTP and DNS protocols
• Java programming

9
Sources

• Datagram and UDP sockets http//www.dsm.fordham.ed
  u/agw/client-server/notes/harold/ch13.txt
• DUMMY DNS
• http//www.unsw.adfa.edu.au/lpb/src/DummyDNS/READ
  ME.html