Controller Based WLANs

Environment- Aruba OS 6.x and above.

Answer-  Here is one of the reason why Clients are unable to view and perform Airplay devices (apple tv, airprinter) though they are in the same subnet.
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AirGroup defines a global CLI configuration knob to control the default global whitelist or blacklist behavior for AirGroup servers. 
This CLI configuration knob would be marked ‘disabled’ by default, as a part of factory default configuration. The factory-default disable value implies a whitelist behavior, wherein all AirGroup servers would be allowed by default. 
This AirGroup configuration command will be available only on the master controller, and the respective local controllers will receive this configuration from the master controller. Thus an administrator will not be able to enable or disable CPPM Enforce Registration knob, on individual local controllers.

Please disable this option if we dont have CPPM to register the device.

(Aruba3400) (config) #no airgroup cppm-server enforce-registration
 
(Aruba3400) #show airgroup s
 
 
AirGroup Enforce Registration
 
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 Status
 ------
Disabled

MDNS logs
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Mar 6 16:20:10 :527000:  <DBUG> |mdns|  mdns_rlist_add 184 record list element add
Mar 6 16:20:10 :527000:  <DBUG> |mdns|  mdns_filter_record 1293 Blacklist this record - drop record
Mar 6 16:20:10 :527000:  <DBUG> |mdns|  mdns_parse_query_packet 1763 mid _universal._sub._ipps._tcp.local dropped: no servers present!
Mar 6 16:20:10 :527000:  <DBUG> |mdns|  mdns_parse_query_packet 1833 There was no response to query from mac:ab:cd:ef:gh:ij:kl, ip: 10.4.12.151