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Advanced Operational Parameters
A-242 41-001160-03, Rev 00, Release 2.4
IP Phone Administrator Guide
DNS Query Setting
Parameter–
sip dns query type
Configuration Files aastra.cfg, <mac>.cfg
Description Specifies the Domain Name Service (DNS) query method to use when the
phone performs a DNS lookup.
Format Integer
Default Value 1
Range 0 A only - The phone sends “A” (Host IP Address) lookup for the IP
address and uses the default port number of 5060.
1 SRV & A - The phone sends “SRV” (Service Location Record) lookup
to get the port number. Most often, the IP address is included in the
response from the DNS server to avoid extra queries. If there is no IP
address returned in the response, the phone sends out the “A” DNS
lookup to find the IP address.
2 NAPTR & SRV & A - First, the phone sends "NAPTR" (Naming
Authority Pointer) lookup to get the “SRV” pointer and service type
(such as "aastra.com SIP+2DT .... _sip.tcp.aastra.net", which means
the service prefers to use TCP and "_sip.tcp.aastra.net" for the SRV
query instead of the default "_sip._tcp.aastra.com"). If the NAPTR
record is returned empty then the default value is used, so in the same
case, the phone will use "_sip._udp.aastra.com" for the next step
lookup.
Next, the phone does SRV lookup to get the IP address and port
number. If there is no IP address in the SRV response then it sends out
and “A” lookup to get it.
Note: On the phone side, if you configure the phone with a Fully- Qualified
Domain Name (FQDN) proxy and specified port, the phone always sends “A
only” lookups to find the Host IP Address of the proxy.
Example sip dns query type: 2
Draft 1