Cisco TelePresence Administrator's Manual page 200

1. The VCS checks its search rules
Any alias, or
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Alias pattern match with a pattern that matches the URI address
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2. The associated target zones are queried, in rule priority order, for the URI.
If one of the target zones is a DNS zone, the VCS attempts to locate the endpoint through a DNS
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lookup. It does this by querying the DNS server configured on the VCS for the location of the domain as
per the URI resolution process via
the request is forwarded to those addresses.
If one of the target zones is a neighbor, traversal client or traversal server zones, those zones are
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queried for the URI. If that system supports URI dialing via DNS, it may route the call itself.
Adding and configuring DNS zones
To enable URI dialing via DNS, you must configure at least one DNS zone. To do this:
1. Go to the Zones page
2. Click New. You are taken to the
3. Enter a Name for the zone and select a Type of DNS.
4. Configure the DNS zone settings as follows:
Field Guidelines
Hop When dialing by URI via DNS, the hop count used is that configured for the DNS zone associated
count with the search rule that matches the URI address (if this is lower than the hop count currently
assigned to the call).
If URI address isn't matched to a DNS zone, the query may be forwarded to a neighbor. In this case,
the hop count used will be that configured for the neighbor zone (if this is lower than the hop count
currently assigned to the call).
H.323 The H.323 and SIP sections allow you to filter calls to systems and endpoints located via this zone,
and SIP based on whether the call is located using SIP or H.323 SRV lookups.
modes
Include This setting determines whether, if no NAPTR (SIP) or SRV (SIP and H.323) records have been
address found for the dialed alias via this zone, the VCS will then query for A and AAAA DNS records before
record moving on to query lower priority zones.
You are recommended to use the default setting of Off, meaning that the VCS will not query for A
and AAAA records, and instead will continue with the search, querying the remaining lower priority
zones. This is because, unlike for NAPTR and SRV records, there is no guarantee that the A/AAAA
records will point to a system capable of processing the relevant SIP or H.323 messages (LRQs,
Setups, etc.) - the system may instead be a web server that processes http messages, or a mail
server that processes mail messages. If this setting is On, when a system is found using A/AAAA
lookup, the VCS will send the signaling to that destination and will not continue the search process.
If the system does not support SIP or H.323, the call will fail.
Zone For most deployments, this option should be left as Default.
profile
5. Click Create zone.
Configuring search rules for DNS zones
If you want your local VCS to use DNS to locate endpoints outside your network, you must:
Cisco VCS Administrator Guide (X7.2)
to see if any of them are configured with a Mode of either:
DNS. If the domain part of the URI address is resolved successfully
(VCS configuration > Zones >
Create zone page.
Dial plan and call processing
Zones).
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