[NCSA-discuss] DNS Questions

[Iztok Umek]

> If I was
> running a nameserver, I wouldn't accept short TTLs. When I
> tried it on my changeover a few days ahead, none of the
> machines accepted the short TTL (yes I updated the serial
> number).
> 
> You might have trouble getting some already uncooperative
> nameserver hoster to change your TTLs anyhow.

The issues are when you are not following the TTL directive. Some people use
low or 0s TTL for SPECIFIC servers on purpose to achieve network load
balancing over multiple ISPs in multihomed environment.

With this it is possible to achieve inbound load balancing based on DNS
resolution. There are many commercial products on the market including
(shameless plug here) Radware who pioneered this approach to network load
balancing across multiple ISPs.

This way not only you can get away with BGP (as an end customer) but truly
get better load balancing and redundancy for your network, not to mention
you can have less then C class assigned to you by ISP and still get it
working just fine. You can even use bunch of cheaper but less reliable
sources, such as cable modem or DSL to augment your T1, T3 ... lines :)