The current default configuration for "Maximum IP addresses in DNS answer" is zero which causes the Traffic Router to return all IP addresses in a cache group to the DNS system for a client. As cache groups grow beyond ~20 caches the responses get too long for some networks and clients to handle. We have seen specific instances where this breaks on the Verizon network.
I suggest we make the default some lower but reasonable number that works in most cases like "3". This is a better default that would work for most small to mid size services. Savvy users who know to change this would be unaffected. But this could save lots of errors for inexperienced users.
I would also suggest that we consider an upper bound limitation like "10" for at least a warning to users trying to configure a hire number. If you have to assign more than this then we should consider decoupling the number of IPs returned from the number of servers that content is hashed across.