os: default arp cache timeout (life)

this was such an obscure find that i thought i'd post it just to refer back to you later. in case you were wondering, 2003 cache holds entries that are invalid for 2 minutes and uses a value of 10 minutes for valid entries. here's the formal info (full reference is in this appendix): ArpCacheLife

• Key: Tcpip\Parameters
• Value Type: REG_DWORD—Number of seconds
• Valid Range: 0–0xFFFFFFFF
• Default: In absence of an ArpCacheLife parameter, the defaults for ARP cache time-outs are a two-minute time-out on unused entries and a ten-minute time-out on used entries.
• Description: See ArpCacheMinReferencedLife