1. Cisco Systems, Inc., Cisco IOS IP Routing: Protocol-Independent Command Reference, "ip route" command documentation. This document confirms the syntax ip route prefix mask {ip-address | interface-type interface-number [ip-address]} [distance]. It specifies that distance is the administrative distance for the route.
2. Cisco Systems, Inc., IP Routing: EIGRP Configuration Guide, Cisco IOS Release 15M&T, "EIGRP Administrative Distance". This guide states, "The administrative distance for an external EIGRP route is 170 by default."
3. Odom, W. (2019). CCNA 200-301 Official Cert Guide, Volume 1. Cisco Press. Chapter 15, "Static Routing," section "Floating Static Routes," explains that a floating static route is configured with a higher administrative distance than the dynamic routing protocol it is intended to back up. Table 15-1 lists the default AD for External EIGRP as 170.