.er is the country code top-level domain (ccTLD) for Eritrea.
2nd level domains
Some second level domains do exist; however their exact expected purposes and possible restrictions are unconfirmed.
com.er, likely for commercial entities/businesses edu.er, likely for educational institutions gov.er, reserved for the Eritrean government mil.er, reserved for the Eritrean military; empty zone (unchanged since August 2004) net.er, likely for network operators/providers org.er, likely for nonprofit organisations ind.er, likely for Eritrean individuals; empty zone (unchanged since August 2004)
References
External links IANA .er whois information Top-Level-Domain .ER: Information about the ccTLD