MacDNS Up & Running
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Using Other
MacDNS features
Load-sharing group
Load sharing allows you to divide incoming
requests among two or more servers, to improve
performance. When you set up MacDNS to perform load
sharing, MacDNS will return the address of one host
out of a group when it is queried for the name of
that group. For example, a site administrator could
install Web servers on three hosts, each with
identical data. The administrator could then assign
a name to the collection of three hosts. MacDNS
would then respond to queries for that name with
one of the three hosts, in round-robin fashion.
This kind of load-sharing arrangement is referred
to as a RAIC system, or redundant array of
independent computers.
For load-sharing groups, the TTL is generally
kept to a small number of seconds. This prevents
information about any one host from dwelling in a
remote cache for a long time and prevents that host
from being swamped by requests due to the cached
information.
To create a load-sharing group:
- In the host list window, Shift-click to
select a group of permanent hosts (Type "Perm")
that you want to have as a load-sharing group.
- Choose Share Load from the Hosts menu. The
Load-Shared Host Information dialog box appears.
- Type the name of the load-sharing group in
the “Shared host name” text box.
- Confirm that the host names in the
“Names of hosts to share the load”
text box are the ones you want. The names appear
automatically; they are the names you selected
in the host list window.
Adding hosts to a load-sharing group
To add new hosts to an existing load-sharing
group:
- In the host list window, select the new
host(s) and Command-click to select
the load-sharing host name.
- Choose Share Load from the Hosts
menu.
- In the dialog box that appears, click OK.
Note: You can also copy and paste new hosts
in the Load-Shared Host Information dialog box.
Select the new host(s) that you are adding to
the load-sharing group and choose Copy from the
File menu. Double-click an entry for a Loadshare
host in the host list window, click in the
“Name of hosts to share the load” box,
and choose Paste from the File menu. Click OK to
accept the change.
Deleting hosts from a load-sharing group
To delete a host from an existing load-sharing
group:
- Select the load-sharing host name in the
host list window.
- In the Load-Shared Host Information dialog
box, select the host(s) you
wish to delete.
- Choose Cut or Clear from the Edit menu; or
press the Delete key
- Click OK.
To Disable/Enable Sharing
If you want to temporarily remove a host from a
sharing group, select the host in the host lists
window, and select Disable Sharing from the
Hosts menu.
You can re-enable sharing by selecting the host
again, and choosing Enable Sharing from the
Hosts menu.
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Mapping Addresses to names
MacDNS automatically maintains reverse domains
for you; there’s no need to create a separate
zone file for your
in-addr.arpa domain, or to
worry about keeping the address-to-name mappings
synchronized.
The MacDNS server will automatically respond to
all pointer queries, which are requests to the name
server to return the correct domain name for a
machine with a specified Internet address. MacDNS
also supports zone transfer requests from a
secondary server for any reverse domain for which
MacDNS is authoritative.
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