single box handling multiple ips, how?

[Ken Hawkins]

Sorry if this is not quite the place to ask however, if it is not can
someone point me toward the right resource (on the net) for answers. I
am
running FreeBSD on a box with an ethernet;
ifconfig
em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
         options=1b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING>
         inet ???.???.???.151 netmask 0xffff0000 broadcast 10.50.255.255
         inet6 fe80::230:48ff:fe2c:76e2%em0 prefixlen 64 scopeid 0x1
         inet ???.???.???.152 netmask 0xffffffff broadcast 10.50.1.152
         inet ???.???.???.153 netmask 0xffffffff broadcast 10.50.1.153
         ether 00:30:48:2c:76:e2
         media: Ethernet 100baseTX <full-duplex>
         status: active

the <???> are just our ips. you will notice that .152 and .153 are
aliases
and are mapped to external ips via a switch. my question is how can I
resolve names to the ip aliases on the box? ie

???.???.???.152 -> a.net

and

???.???.???.153 -> b.net

is this a /etc/hosts kind of entry?

???.???.???.152    web1.a.net web1
???.???.???.152    web1.a.net.
???.???.???.153    web1.b.net web1
???.???.???.153    web1.b.net.

any help would be greatly appreciated!

ken;