Trying to find the reason behind server shutdown

Our Centos server shut down and the web host support had to start the server. However, they said they couldn't identify what had caused the server shutdown. I tried this command to see when the server was last booted up: [root@xxxxxxx log]# last -x reboot reboot system boot 3.10.0-1160.15.2 Fri May 4 18:03 - 20:35 (02:31)
So, 18:03 is when the support started the server. This looks right to me. I checked /var/log/messages: May 4 17:38:49 xxxxxxx p0f: [!] WARNING: Too many tracked connections, deleting 101. Use -m to adjust. May 4 17:38:49 xxxxxxx p0f: [!] WARNING: Too many tracked connections, deleting 101. Use -m to adjust. May 4 17:38:49 xxxxxxx kernel: ERROR anon_vma num_children for anon_vma ffff880002a93460 3 > 2 May 4 17:38:49 xxxxxxx p0f: [!] WARNING: Too many tracked connections, deleting 101. Use -m to adjust. May 4 17:38:50 xxxxxxx p0f: [!] WARNING: Too many tracked connections, deleting 101. Use -m to adjust. May 4 17:38:50 xxxxxxx p0f: [!] WARNING: Too many tracked connections, deleting 101. Use -m to adjust. ^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@ May 4 18:03:40 xxxxxxx journal: Runtime journal is using 8.0M (max allowed 199.6M, trying to leave 299.4M free of 1.9G available ? currentlimit 199.6M). May 4 18:03:40 xxxxxxx kernel: Initializing cgroup subsys cpuset May 4 18:03:40 xxxxxxx kernel: Initializing cgroup subsys cpu May 4 18:03:40 xxxxxxx kernel: Initializing cgroup subsys cpuacct
There were no entries recorded in the logs right after 17:38:50 and were indicated by ^@^@^@^@^@. Looks like the server had shut down at 17:38:50. Is there a way to find out what had caused the server to shut down? Does anything in /var/log/messages entries above indicate the reason behind the shutdown?