Dns Effects On Web Site Performance And Availability - MACROMEDIA COLDFUSION 4.5-ADMINISTRING COLDFUSION SERVER Manual

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reside on the database server. In short, tune your databases and queries for
maximum efficiency.

DNS effects on Web site performance and availability

Improper Domain Name System (DNS) setup and configuration on Web servers is one
of the most common problems administrators encounter. This section addresses the
following topics:
What is DNS
DNS effects on site performance and availability
DNS core elements
What is DNS
DNS is a set of protocols and services on a TCP/IP network that allows network users to
use hierarchical natural language names rather than computer IP addresses when
searching for other computer hosts (servers) on the network. DNS is used extensively
on the Internet as well as on private enterprise networks, including LANs and WANs.
The primary capability contained within DNS is its ability to map host names to IP
addresses, and vice-versa. For example, suppose the Web server at Allaire has an IP
address of 157.55.100.1. Most people would connect to this server by entering the
domain name (www.allaire.com) and not the less friendly IP address. Besides being
easier to remember, the name is more reliable because the numeric address could
change for a variety of reasons, but the name can always be reserved.
DNS effects on site performance and availability
Internet DNS is a powerful and successful mechanism that has enabled huge numbers
of individuals and organizations to create easily locatable Web sites on the Internet.
However, DNS by itself may not allow your Web site to perform and scale as it needs to,
thus causing it to become unavailable and unreliable. Whether or not you use DNS by
itself to load balance inbound traffic depends largely on the site's purpose and the
amount of concurrent activity you expect on it. For instance, a low volume, static site
that only provides textual HTML information can likely be accommodated just fine by
round-robin DNS. However, a high volume, dynamic, e-commerce site that you
anticipate doing lots of volume likely won't perform or scale well ultimately if its only
supported by round-robin DNS.
To understand why, let's look further at the e-commerce example. Even if you have
planned ahead and set up multiple servers to support this high volume site, if you rely
only on DNS, it can only do two things: translate the natural language names to server
IP address mappings so that users can find the site, and if you've enabled round-robin
distribution for multi-server load balancing, it can distribute the load among each
1. Suhy, Scott and Glenn Wood. "DNS and Microsoft Windows NT 4.0: A White Paper." Redmond, WA:
Microsoft Corporation. 1996. Much of the DNS overview material presented in this chapter comes
from Suhy and Wood's white paper.
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