Summary
ch.pdx.edu is a domain controlled by four nameservers. Some of them are on the same IP network.
co.gy,
co.mz,
ac.mz,
co.ci,
nic.do and at least 61 other hosts share nameservers with this domain.
pdx.edu is delegated to three nameservers, however one extra nameserver is listed in the zone. Some of them are on the same IP network. Incoming mail for
pdx.edu is handled by one mailserver at
pdx.edu themselves.
pdx.edu has one IP number.