Cisco Cisco ASR 5500 Guía Para Resolver Problemas

example.example.com

1500 IN A 1.1.1.1

The Name Authority Pointer (NAPTR) resource record and is a powerful tool that allows Domain Name
System (DNS) to be used in order to look up services for a wide variety of resource names that are not in the
Domain Name (DN) syntax.

The Straightforward−NAPTR (S−NAPTR) procedure is used for the resolution of a DN, application service
name, or application protocol dynamically in order to target the server and port via both NAPTR and Service
(SRV).

Here is an example:

starent.apn.epc.mnc012.mcc345.3gpp.org

             order pref flags

2000 IN NAPTR 100 10   "s"   "SGW:PMIP"           ( ; service

                         ""                          ; regexp

                         pmip.example.com.           ; replacement

                                                  )    

The SRV resource record uses a pool of servers for a single domain with static load balancing to each server
in order to move services from host to host and in order to designate some hosts as primary servers for a
service from a pool of hosts.

Here is an example:

pmip.example.com

           Pref Weight Port Target

1500 IN SRV 10   0     10000 example.example.com.

This image illustrates the PGW selection by the MME for the initial Attach message and the additional Public
Data Network (PDN) connection: