September 2000
Intermediate to advanced
352 pages
6h 41m
English
book
OpenView Network Node Manager: Designing and Implementing an Enterprise Solution
by John Blommers
Content preview from OpenView Network Node Manager: Designing and Implementing an Enterprise Solution
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Reliability Designs for DNS
DNS is a mission-critical service. Networked applications depend on it and NNM is no exception. The architecture of DNS provides several mechanisms to ensure reliability of the service:
client access to multiple name servers
caching at the name server
primary and secondary name servers
To understand how these architectural elements provide reliability, consider the client-server DNS model first. An application (such as telnet, ftp, NNM, Navigator, and sendmail) that needs to connect to another system by name is a DNS client. This client code is known as the resolver and it is guided by an editable configuration file called resolv.conf (that’s resolve without the last letter) in UNIX. resolv.conf defines the following ...