The restart occurs due to DNS resolution failure. In this case, for a host that does not have an IPv6 address, the DNS resolution returns a NULL pointer, which is then deferenced.
This is B#161610 and has been fixed in :
- SGOS 220.127.116.11
- SGOS 18.104.22.168 and newer SG 5.5.x versions
SGOS 6.x is not affected by this.