Yealink SIP-T52S Administrator's Guide

Configuring Advanced Features
767
Parameters
Permitted Values
Default
None
Phone User Interface:
None
Static DNS Cache
Failover redundancy can only be utilized when the configured domain name of the server is
resolved to multiple IP addresses. If the IP phone is not configured with a DNS server, or the
DNS query returns no result from a DNS server, you can statically configure a set of DNS
NAPTR/SRV/A records into the IP phone. The IP phone will attempt to resolve the domain
name of the SIP server with static DNS cache.
When the IP phone is configured with a DNS server, it will behave as follows to resolve domain
name of the server:
 The IP phone performs a DNS query to resolve the domain name from the DNS server.
 If the DNS query returns no results for the domain name, or the returned record cannot
be contacted, the values in the static DNS cache (if configured) are used when their
configured time intervals are not elapsed.
 If the configured time interval is elapsed, the IP phone will attempt to perform a DNS
query again.
 If the DNS query returns a result, the IP phone will use the returned record from the DNS
server and ignore the statically configured cache values.
When the IP phone is not configured with a DNS server, it will behave as follows:
 The IP phone attempts to resolve the domain name within the static DNS cache.
 The IP phone will always use the results returned from the static DNS cache.
Support for negative caching of DNS queries as described in RFC 2308 is also provided to allow
faster failover when prior DNS queries have returned no results from the DNS server.
IP phones can be configured to use static DNS cache preferentially. Static DNS cache is
configurable on a per-line basis.

Yealink SIP-T52S Specifications

General

Touchscreen	-
Display diagonal	2.8 \
Backlight display	Yes
Display resolution	320 x 240 pixels
Lines quantity	16 lines
Phonebook capacity	1000 entries
Number of VoIP accounts	12
AC adapter input voltage	100 - 240 V
Bluetooth version	2.1+EDR
Security algorithms	802.1x RADIUS, HTTPS, MD5
Ethernet LAN interface type	Gigabit Ethernet
USB 2.0 ports quantity	1
Ethernet LAN (RJ-45) ports	2
Mounting	Desk/Wall
Handset type	Wired handset
Product type	IP Phone
Product color	Black
Voice codecs	G.722, G.723, G.723.1, G.726, OPUS, iLBC
Volume control	Digital
Operating temperature (T-T)	-10 - 40 °C
Operating relative humidity (H-H)	10 - 95 %
Cables included	LAN (RJ-45)
Number of handles included	1 pc(s)
Front camera	No
Operating system installed	Linux

Weight and Dimensions

Depth	212 mm
Width	211.6 mm
Height	166.8 mm