DNS Configuration and Management Manual (G06.27+, H06.05+, J06.03+)

DNS and BIND Basics
HP DNS Configuration and Management Manual—529432-003
A-6
The Resolution Process
4. The name server demon, named, receives the query from the resolver. Because
the name server has information about only the hosts in its local domain (nmt.edu),
it cannot answer the query using the information in its local database.
5. The local name server queries a root name server to find the address of
indigo.div.inc.com. The root name server serves the root domain. The root
name server typically stores information about hosts and name servers one and
two levels below the root.
6. If the root name server cannot resolve the host name, it returns the address of a
name server for the
inc.com domain.
7. The local name server queries the server for the
inc.com domain to find the
address of
indigo.div.inc.com.
8. The name server for the
inc.com domain may not contain information for the
div.inc.com domain. If so, it returns the address of a name server for the
div.inc.com domain.
9. The local name server queries the server for the
div.inc.com domain to find the
address of
indigo.div.inc.com.
10. The server for the
div.inc.com domain returns the address of
indigo.div.inc.com to the local name server.
11. The local name server passes host indigo’s address to the resolver, which passes
the address to
gethostbyname, which returns the address to the telnet process.
The local name server in the
nmt.edu domain caches the addresses of the remote
name servers, so that the next time a local user needs the address of a host in the
inc.com domain, the local name server sends its query directly to the name server for
inc.com instead of querying the root name server.
The Resolution Process
This subsection describes various aspects of the BIND resolution process.
BIND allows you to enter host names that are not fully qualified because typing
complete domain names is cumbersome; that is, host names that do not contain every
label from the host to the root and end with a dot.
To resolve a host name, BIND uses the following methods:
•
If the input host name ends with a dot, the name server looks up the input host
name as is, without appending any domains to the host name.
•
If the input host name contains the number of dots specified by the ndots option in
the /etc/resolv.conf file, BIND looks it up as is, before appending any domains to
Note. It is always correct to use a name that contains all the labels from the host to the root
and does not end with a dot. Names that end in a dot are not allowed in mail addresses and
network-related configuration files. To facilitate the lookup process, you can use names that
contain all the name components and end with a dot in commands like dig, ping, and telnet.