Uhm, no. Don't do that.
Second Life is apparently using Akami Edgesuite. The IPv4 address returned by DNS for login.agni.lindenlab.com will vary by location. The two addresses I get for that fully-qualified-domain-name (FQDN) are 69.27.204.9 and 69.27.204.26. BOTH of those "login servers" are not functioning properly.
In order for me to login to Second Life I have edited the hosts file on my Windows PC so that the local resolver stub running in Windows returns an IP address of my choosing instead of making a DNS query for one. You can use one of the many "DNS test" web sites to get the results of DNS lookups from other locations. Pick an address and try it in hosts by adding it to the end of the file:
A.B.C.D login.agni.lindenlab.com
Better still: @Monty Linden @Linden Lab Is this a "poke somebody with a stick" offense? Software malfunction?