SSCA Registration Process 4

Question 1

How does a UA de-register all of its active bindings at once from a registrar?

Accepted Answer

Send REGISTER with Contact: * and Expires: 0

Answer

Using 'Contact: *' with 'Expires: 0' is the wildcard de-registration method defined in RFC 3261 that removes all bindings for the AOR.

Question 2

What is a SIP 'binding' as managed by a registrar?

Accepted Answer

The association between an AOR and one or more Contact URIs with an expiration time

Answer

A binding maps an Address-of-Record to a device-specific Contact URI and has a lifetime controlled by the Expires value.

Question 3

Can a single SIP Address-of-Record (AOR) have multiple simultaneous bindings?

Accepted Answer

Yes, multiple Contact URIs with different q-values can be registered simultaneously

Answer

RFC 3261 allows multiple bindings per AOR; the q-value parameter on each Contact indicates relative preference for routing.

Question 4

What does the 'q' parameter in a Contact header indicate during SIP registration?

Accepted Answer

The relative preference (priority) of that contact URI when multiple are registered

Answer

The q-value (0.0–1.0) indicates priority; higher q-values are tried first when the registrar or proxy forks requests to multiple bindings.

Question 5

What happens to a specific binding when a UA sends a REGISTER with Expires: 0 for that single Contact URI?

Accepted Answer

Only that specific Contact URI binding is removed

Answer

Setting Expires: 0 for a specific Contact URI removes only that binding, leaving other bindings for the same AOR intact.

(SSCA) Sip School Certified Associate Practice Test