HSRP and VRRP have one router actively forwarding for the virtual IP while the others sit idle. GLBP (Gateway Load Balancing Protocol) is different - it can use ALL routers in the group simultaneously. One router is the Active Virtual Gateway
A specific static route to a remote loopback is the simplest possible deterministic routing test. The loopback as the ping source proves end-to-end reachability with a stable address. This lab walks through configuring static routes across R1, R2,
By default, OSPF neighbors will form an adjacency with anyone speaking the protocol on the same segment. In a production network that is a security risk - anyone with link access can inject routing updates. OSPF authentication adds a shared secret
EIGRP's signature feature is sub-second convergence on common failure modes. The secret: DUAL (Diffusing Update Algorithm) precomputes loop-free backup paths called Feasible Successors (FS). When the primary path (Successor) fails, EIGRP instantly switches to the FS
EIGRP (Enhanced Interior Gateway Routing Protocol) is Cisco's dynamic routing protocol. It uses the DUAL algorithm (Diffusing Update Algorithm) and combines distance-vector simplicity with link-state-grade convergence. Originally Cisco-only; now an open IETF informational standard
Multi-area OSPF divides a network into smaller logical zones connected through Area 0 (the backbone). Each non-backbone area connects to Area 0 through an Area Border Router (ABR), which maintains the LSA databases for both areas and summarizes
RIP (Routing Information Protocol) is the dynamic routing protocol every textbook teaches first because it is the simplest. Distance-vector, hop count metric, max 15 hops, periodic full updates every 30 seconds. RIPv2 added classless support and authentication. Nobody designs
On a broadcast OSPF segment, the protocol elects a Designated Router (DR) and a Backup DR (BDR). Other routers form adjacencies only with the DR/BDR rather than with every neighbor on the segment, dramatically reducing LSA flooding. The election
OSPF operates differently on different link types. On Ethernet (broadcast), it elects a DR/BDR. On a point-to-point link (PPP, P2P serial, GRE), no election - both ends form an adjacency directly. There are also non-broadcast (NBMA) types
The CCNA exam requires a working understanding of wireless network architecture without a hands-on Wi-Fi lab requirement. The Catalyst 9800 Wireless Controller + lightweight access point design that defines modern Cisco wireless is too large for the CML Free
An SVI (Switched Virtual Interface) is a virtual L3 interface inside a switch, associated with a VLAN. When the switch is enabled for IP routing, the SVI becomes the gateway for hosts in that VLAN - just like a router interface,
A floating static route is a second static route to the same destination with a deliberately higher administrative distance. It sits in the configuration but stays out of the routing table - "floating" - until the primary route disappears. The