53
D14049.05
February 2009
Grey Headline
(continued)
TANDBERG
VIDEO COMMUNICATIONS SERVER
ADMINISTRATOR GUIDE
Introduction
Getting started
Overview and
status
System
configuration
VCS
configuration
Zones and
neighbors
Call
processing
Bandwidth
control
Firewall
traversal
Appendices
Applications
Maintenance
System configuration
The
DNS
page allows you to configure
the VCS's DNS servers and local
domain name.
To go to the
DNS
page:
System configuration > DNS
•
To configure DNS settings using the
CLI:
xConfiguration IP DN
•
S
About DNS servers
You must specify at least one DNS
server to be queried for address
resolution if you wish to either:
use FQDNs (Fully Qualified Domain
•
Names) instead of IP addresses
when specifying external addresses
(for example for LDAP and NTP
servers, neighbor zones and
alternates), or
use features such as
•
URI dialing
or
ENUM dialing
.
You can specify up to 5 DNS servers.
The VCS sends requests to all
configured servers in parallel taking the
first result received and discounting
the rest.
!
This can lead to confusing
behavior should local network
administrators, for example,
deploy ‘split horizon’ DNS where
records held on an internal, corporate,
DNS server use the same domain
names but with different values to
those on the public internet - an often
used tactic in corporate intranets.
About the DNS domain name
The DNS
Domain Name
is used when
attempting to resolve server addresses
configured on the VCS that are without
any form of qualification (e.g.
ldap
or
ldap_server
but not
ldap.server
). It
applies only to the following:
LDAP server
•
NTP server
•
External Manager server
•
Remote logging server.
•
The DNS
Domain Name
is appended to
the unqualified server address before a
query to the DNS server is executed.
If the server address is an IP address
or is in the format of a domain name,
DNS will only be queried for the server
address as configured, without the
DNS
Domain Name
appended. For this
reason we recommend that all server
addresses use an IP address or FQDN
(Fully Qualified Domain Name).
The DNS Domain name plays no part in
URI dialing.
DNS
The
Time
page allows you to configure the VCS to use
an NTP server, and to set the local time zone. These
settings determine the VCS's local time and date, which
is used throughout the web interface and to set the
timestamp that appears at the start of each line in the
Event Log and Configuration Log.
To go to the
Time
page:
System configuration > Time
•
To configure these settings using the CLI:
xConfiguration NTP Addres
•
s
xConfiguration TimeZone Nam
•
e
About the NTP server
The NTP server is a remote server with which the VCS
synchronizes in order to ensure its time setting is
accurate. The NTP server provides the VCS with UTC
time.
Accurate timestamps play an important part in H.323
authentication
, helping to guard against replay attacks.
For this reason, if you are using authentication in a
deployment that includes H.323, both the VCS and the
endpoints must use an NTP server to synchronize their
system time.
!
Traversal clients must always authenticate with
traversal servers, even if the server’s
Authentication Mode
is
Off
. Therefore in order
for a traversal client and traversal server to connect to
each other, both must be configured with details of an
NTP server.
SIP-only deployments do not require the use of
NTP for authentication.
To configure the VCS with an NTP server, on the
Time
page enter the IP address or FQDN (or server address,
if a DNS
Domain Name
has also been configured) of the
NTP server
to be used when synchronizing system time.
If no NTP server has been configured, the VCS will use
its own operating system time to determine the local
time and date.
About the time zone
The NTP server provides the VCS with UTC time. You
can also determine the local time to be used on your
system by configuring the
Time Zone
.
This takes the
UTC time and offsets it by the number of hours specified
by the selected time zone to make the local time.
System time
The VCS's
System time
is based on the VCS's operating
system time, which will have been synchronised using an
NTP server if one has been configured. System time is
always UTC.
The UTC system time is shown at the bottom left of
each page in the web interface, is also used as a
timestamp at the end of each entry in the Event Log and
Configuration Log.
Local time
The VCS's local time is based on the VCS's system time,
offset by the configured
Timezone.
Local time is used is used throughout the web interface
and to set the timestamp that appears at the start of
each line in the Event Log and Configuration Log.
Daylight saving/summer time
If you have selected a time zone other than GMT, the
VCS will automatically update its local time to account
for summer time (also known as daylight saving time).
Time
