Hi, SRV records are basically used for identifying the host(s) (also the port) on which the service (SIP here) is being hosted in the domain. When the host part of a URI contains a numeric IP or Port it indicates that the "host part" is a 'host' and not a 'domain'. That is the reason why RFC says that you should do A record query directly in such cases. In your case, if you are sure that the host part of URI is _always_ a host and not a domain name then you can use A/AAAA/A6 record query directly. Otherwise you should do a SRV query first to get the host and then do A/AAAA/A6 query to get the actual IP address. (If you do a A record query directly on a domain, you might endup getting IP of its Name Server instead of its SIP server.) Rgds, ~Lalith [EMAIL PROTECTED] wrote on 11/02/2004 06:06:27 PM: > Hello, > > Suppose Bob(User A) wants to reach [EMAIL PROTECTED](User B). > The transport type and the port on which the session is to be > established is also preconfigured. > Does Bob need to do a plain DNS query (A ecord lookup) to determine the > ip address or he needs to do an SRV query ? > > Below is the section extracted from rfc 3263, whch says when a port is > explicitly specified, we need to do a A or AAAA record look up than > doing a SRV query. > > "If the TARGET was not a numeric IP address, but a port is present in > the URI, the client performs an A or AAAA record lookup of the domain > > name. The result will be a list of IP addresses, each of which can > be contacted at the specific port from the URI and transport protocol > > determined previously. The client SHOULD try the first record. If > an attempt should fail, based on the definition of failure in Section > > 4.3, the next SHOULD be tried, and if that should fail, the next > SHOULD be tried, and so on. > > This is a change from RFC 2543. Previously, if the port was > explicit, but with a value of 5060, SRV records were used. Now, A > > or AAAA records will be used." > > Is DNS SRV query required here ? > > Thanks in advance, > Prabha N > > > > > > > > > > > _______________________________________________ > Sip-implementors mailing list > [EMAIL PROTECTED] > http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors *********************** HSS-Unclassified *********************** "DISCLAIMER: This message is proprietary to Hughes Software Systems Limited (HSS) and is intended solely for the use of the individual to whom it is addressed. It may contain privileged or confidential information and should not be circulated or used for any purpose other than for what it is intended. If you have received this message in error, please notify the originator immediately. If you are not the intended recipient, you are notified that you are strictly prohibited from using, copying, altering, or disclosing the contents of this message. HSS accepts no responsibility for loss or damage arising from the use of the information transmitted by this email including damage from virus." _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
