Randomization of P-CSCF Addresses from DNS

The SMF service supports random selection of resolved hosts. If a DNS resolution yielded a set of IP addresses for a host and if the randomize-answers CLI is enabled in the DNS Proxy profile configuration, the DNS lookup selects IP addresses randomly. The selection of addresses is based on pseudo-random permutation of integers that ensure randomization.

Every DNS query for a particular host gives different sets of IP addresses when the randomize-answers CLI is enabled. This is applicable for both IPv4 and IPv6 addresses.

The selection method is either round-robin or randomized for the DNS Proxy profile.

Example:

For a DNS lookup to get a subset of five IP addresses with randomize-answers enabled.

Host1 = { "209.165.200.226", "209.165.201.2", "209.165.201.3", "209.165.201.4", "209.165.201.5", "209.165.201.6", "209.165.201.7", "209.165.201.8", "209.165.201.9", "209.165.201.10" }

First lookup: [209.165.201.5 209.165.200.226 209.165.201.9 209.165.201.2 209.165.201.7]

Second lookup: [209.165.201.8 209.165.201.6 209.165.201.2 209.165.201.3 209.165.201.9]

Third lookup: [209.165.201.7 209.165.201.5 209.165.201.2 209.165.201.4 209.165.201.9]