AudioCodes Mediant 4000 SBC User Manual page 370

Parameter
[ProxySet_ClassificationInput]
DNS Resolve Method
dns-resolve-method
[ProxySet_DNSResolveMetho
d]
User's Manual
according to IP address only.

[1] IP Address, Port & Transport Type = Classifies calls to the
Proxy Set according to IP address, port, and transport type.
Note:

The parameter is applicable only if the IP Groups table's
parameter, 'Classify by Proxy Set' is set to Enable (see
Configuring IP Groups on page 349).

If more than one Proxy Set is configured with the same IP
address and associated with the same SIP Interface, the device
may classify and route the SIP dialog to an incorrect IP Group. In
such a scenario, a warning is generated in the Syslog message.
However, if some Proxy Sets are configured with the same IP
address but different ports (e.g., 10.1.1.1:5060 and
10.1.1.1:5070) and the parameter is configured to IP Address,
Port & Transport Type, classification to the correct IP Group is
achieved. Therefore, when classification is by Proxy Set, pay
attention to the configured IP addresses and this parameter.
When more than one Proxy Set is configured with the same IP
address, the device selects the matching Proxy Set in the
following order:

Selects the Proxy Set whose IP address, port, and transport
type match the source of the incoming dialog (regardless of
the settings of this parameter).

If no match is found for above, it selects the Proxy Set whose
IP address and transport type match the source of the
incoming dialog (if the parameter is configured to IP Address
Only).

If no match is found for above, it selects the Proxy Set whose
IP address match the source of the incoming dialog (if the
parameter is configured to IP Address Only.
Defines the DNS query record type for resolving the proxy server's
host name (FQDN) into an IP address(es).

[-1] = Not configured. DNS resolution method is according to the
settings of the global parameter, ProxyDNSQueryType.

[0] A-Record = (Default) DNS A-record query is used to resolve
DNS to IP addresses.

[1] SRV = If the proxy address is configured with a domain name
without a port (e.g., domain.com), an SRV query is done. The
SRV query returns the host names (and their weights). The
device then performs DNS A-record queries per host name
(according to the received weights). If the configured proxy
address contains a domain name with a port (e.g.,
domain.com:5080), the device performs a regular DNS A-record
query.

[2] NAPTR = NAPTR query is done. If successful, an SRV query
is sent according to the information received in the NAPTR
response. If the NAPTR query fails, an SRV query is done
according to the configured transport type. If the configured proxy
address contains a domain name with a port (e.g.,
domain.com:5080), the device performs a regular DNS A-record
query. If the transport type is configured for the proxy address, a
NAPTR query is not performed.

[3] Microsoft Skype for Business = SRV query as required by
Microsoft when the device is deployed in a Microsoft Skype for
370
Mediant 4000 SBC
Description
Document #: LTRT-40203