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 = { "1.1.1.1", "2.2.2.2", "3.3.3.3", "4.4.4.4", "5.5.5.5", "6.6.6.6", "7.7.7.7", "8.8.8.8", "9.9.9.9", "10.10.10.10" }
First lookup: [5.5.5.5 1.1.1.1 9.9.9.9 2.2.2.2 7.7.7.7]
Second lookup: [8.8.8.8 6.6.6.6 2.2.2.2 3.3.3.3 9.9.9.9]
Third lookup: [7.7.7.7 5.5.5.5 2.2.2.2 4.4.4.4 9.9.9.9]