Grandstream Networks GXV3240 Administration Manual page 50

DNS Mode
DNS SRV Fail-over Mode
NAT Traversal
Defines which DNS service will be used to lookup IP address for SIP
server's hostname. It can be selected from the dropdown list:
•
A Record
•
SRV
•
NATPTR/SRV
If it needs DNS SRV resource, which DNS server response more than one
result, it should be set to "SRV" or "NATPTR/SRV".
The default setting is "A Record".
The option will decide which IP is going to be used in sending subsequent
SIP packets (ex: Register refresh requests) after the list of IPs for SIP
server host is resolved with DNS SRV.
Default (prefer server with lowest SRV priority):
The phone will always prefer to send SIP requests to the available server
having the lowest priority, and in case it's down it contacts the next one,
but once the server having lowest priority is UP again, the phone will switch
over to this one.
Saved one until DNS TTL (Stay on responding IP until DNS timeout):
On this mode, the phone will resolve DNS SRV records and tries to send
the request to the server having lowest priority and if it doesn't respond, it
will move on to the next IP until one of the servers responds, once this
happen the phone will keep contacting this responding IP until DNS timeout
(30 minutes) before starting over.
Saved one until no response (Stay on responding IP until its failure):
On this mode, the phone will send SIP requests to the last responding IP,
and it doesn't failover/switchover to the next one until this responding
server is down.
Specifies which NAT traversal mechanism will be enabled on the phone
system. It can be selected from the dropdown list:
•
NAT NO
•
STUN
•
Keep-alive
•
UPnP
•
Auto
•
VPN
If the outbound proxy is configured and used, it can be set to "NAT NO".
If set to "STUN" and STUN server is configured, the phone system will
periodically send STUN message to the SUTN server to get the public IP
address of its NAT environment and keep the NAT port open.
STUN will not work if the NAT is symmetric type.
GXV3240 Administration Guide
Version 1.0.3.207
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