Configuring Static Routes – Complete Cisco IOS Guide

1. What Is Static Routing?

Static routing is the manual configuration of routes in a router’s routing table. Instead of learning paths automatically through a dynamic protocol like OSPF or EIGRP, the administrator explicitly tells the router: “to reach network X, send traffic to next-hop Y via interface Z.”

Static routes have an Administrative Distance of 1 by default — the lowest of any routing source except directly connected interfaces (AD 0). This means a static route will always override a dynamic protocol’s route to the same destination unless the static route’s AD is manually raised (floating static).

When to use static routing:

• Stub networks — a branch with only one exit point; no need for a routing protocol
• Default gateway to the Internet — one static default route (0.0.0.0/0) handles all Internet-bound traffic
• Point-to-point links — serial or leased-line links where only one path exists
• Backup paths — floating static routes sit dormant while the primary dynamic route is active
• Security-sensitive environments — no routing protocol traffic means less exposure
• Small networks — fewer than 5–10 routers where dynamic protocol overhead is not justified

Related pages: show ip protocols | Administrative Distance | Default Routes | OSPF Overview | show ip route | show ip interface brief | show running-config | Wildcard Masks | Static Routing Configuration Lab

2. ip route Command Syntax

ip route <destination-network> <subnet-mask> {<next-hop-IP> | <exit-interface> | <exit-interface next-hop-IP>} [AD]
            

3. Three Configuration Methods – Compared

Method A – Next-Hop IP Only (Multi-Access Networks)

ip route 192.168.2.0 255.255.255.0 192.168.1.2
            

The router knows the destination is reached via IP 192.168.1.2, but it must perform a recursive lookup to find which local interface leads to that next-hop. Best for Ethernet (multi-access) networks where the next-hop IP is on a directly connected subnet.

Method B – Exit Interface Only (Point-to-Point Links)

ip route 192.168.2.0 255.255.255.0 GigabitEthernet0/0
            

The router forwards out Gi0/0 and treats the entire exit interface as directly connected. Fine on serial (HDLC/PPP) point-to-point links, but avoid on Ethernet — on a broadcast network this causes the router to ARP for every destination IP individually, flooding the ARP cache.

Method C – Fully Specified: Interface + Next-Hop (Recommended)

ip route 192.168.2.0 255.255.255.0 GigabitEthernet0/0 192.168.1.2
            

The most explicit and performant option. The router knows both the exit interface and the next-hop, so no recursive lookup is needed and ARP flooding is avoided. Use this on all Ethernet links.

4. Recursive vs. Directly Connected Static Routes

5. Default Static Route (Gateway of Last Resort)

A default route matches any destination that has no more specific entry in the routing table. It acts as the “gateway of last resort” — typically pointing toward an ISP or upstream router for all Internet-bound traffic.

! Default static route (IPv4) — matches any destination not in the routing table
ip route 0.0.0.0 0.0.0.0 203.0.113.1

! Verify it is installed as gateway of last resort
Router# show ip route
! Gateway of last resort is 203.0.113.1 to network 0.0.0.0
! S*   0.0.0.0/0 [1/0] via 203.0.113.1   ← S* = static default route
            

The 0.0.0.0 0.0.0.0 mask matches every possible destination address — it is the widest possible prefix. The router uses the longest prefix match rule, so a more specific route always wins over the default.

6. Host Route (/32)

A host route uses a /32 mask (255.255.255.255) to point to a single specific IP address rather than a network. Common uses include routing to a loopback interface, directing traffic to a specific server, or creating precise firewall bypass rules.

! Route to a specific host (single IP address)
ip route 192.168.2.10 255.255.255.255 192.168.1.2

! Verify — appears in routing table as /32
Router# show ip route 192.168.2.10
! S    192.168.2.10/32 [1/0] via 192.168.1.2
            

7. Floating Static Route (Backup Path)

A floating static route is a static route with an AD set higher than the primary dynamic routing protocol. While the primary route is active (lower AD wins), the floating static is hidden from the routing table. If the primary route disappears (e.g., OSPF neighbour fails), the floating static automatically “floats” into the table as the backup.

! Primary route learned via OSPF (AD 110) — active in routing table
! Floating static backup (AD 150 > OSPF’s 110) — dormant while OSPF is active
ip route 192.168.2.0 255.255.255.0 192.168.3.1 150

! If OSPF goes down, routing table shows:
! S    192.168.2.0/24 [150/0] via 192.168.3.1   ← floating static activates
            

  Normal operation:
  Routing table: O 192.168.2.0/24 [110/2] via 192.168.1.2   (OSPF wins; AD 110 < 150)
  Floating static: hidden (AD 150)

  OSPF neighbour fails:
  Routing table: S 192.168.2.0/24 [150/0] via 192.168.3.1   (backup activates)
            

Set the floating static AD just above the primary protocol’s AD: for OSPF (110) use 120; for EIGRP (90) use 100. Never use AD 255 — that makes the route permanently unusable.

8. Two-Router Static Route Example

  LAN A: 192.168.1.0/24        Link: 10.0.12.0/30          LAN B: 192.168.2.0/24
  [R1] Gi0/1: 192.168.1.1 —— Gi0/0: 10.0.12.1 ———— Gi0/0: 10.0.12.2 Gi0/1: 192.168.2.1 [R2]
            

! ===== R1 =====
! R1 needs a route to reach LAN B (192.168.2.0/24) — next hop is R2’s Gi0/0 IP
ip route 192.168.2.0 255.255.255.0 GigabitEthernet0/0 10.0.12.2

! Default route toward Internet (if R1 is the edge router)
ip route 0.0.0.0 0.0.0.0 203.0.113.1


! ===== R2 =====
! R2 needs a route back to LAN A (192.168.1.0/24)
ip route 192.168.1.0 255.255.255.0 GigabitEthernet0/0 10.0.12.1

! OR — R2 can use a default route pointing back to R1 for all non-local traffic
ip route 0.0.0.0 0.0.0.0 10.0.12.1


! ===== Verification on R1 =====
R1# show ip route
! Gateway of last resort is 203.0.113.1 to network 0.0.0.0
!
! S*   0.0.0.0/0 [1/0] via 203.0.113.1
! C    10.0.12.0/30 is directly connected, GigabitEthernet0/0
! C    192.168.1.0/24 is directly connected, GigabitEthernet0/1
! S    192.168.2.0/24 [1/0] via 10.0.12.2, GigabitEthernet0/0
            

9. IPv6 Static Routes

IPv6 static routes follow the same principles as IPv4 but use the ipv6 route command and IPv6 prefix notation:

! Syntax:
ipv6 route <destination-prefix/length> {<next-hop-IPv6> | <exit-interface> | <exit-interface next-hop-IPv6>} [AD]

! Route to a specific IPv6 network
ipv6 route 2001:db8:2::/64 2001:db8:1::2

! IPv6 default route (matches all IPv6 destinations)
ipv6 route ::/0 2001:db8:1::1

! Fully specified IPv6 static route (recommended on Ethernet)
ipv6 route 2001:db8:2::/64 GigabitEthernet0/0 2001:db8:1::2

! Verify IPv6 routing table
Router# show ipv6 route
            

Important: IPv6 unicast routing is disabled by default on Cisco IOS. Enable it first:

Router(config)# ipv6 unicast-routing
            

10. Redistributing Static Routes into Dynamic Protocols

In mixed environments where some routers use static routes and others use dynamic routing protocols, you can redistribute static routes into the dynamic protocol so other routers learn them automatically.

! Redistribute static routes into OSPF (includes the subnets keyword to carry prefix info)
router ospf 1
 redistribute static subnets

! Redistribute static routes into EIGRP
router eigrp 100
 redistribute static metric 10000 100 255 1 1500

! Redistribute static routes into RIP
router rip
 redistribute static
            

Caution: Redistributing a default static route into OSPF requires the default-information originate command, not redistribute static.

11. Verification Commands

! View all routes; static routes are marked S (or S* for default)
Router# show ip route

! View only static routes
Router# show ip route static

! Check if a specific route exists
Router# show ip route 192.168.2.0

! Verify the interface used to reach the next-hop is up
Router# show ip interface brief

! Check the full static route commands in the running config
Router# show running-config | include ip route

! Test reachability through the static route
Router# ping 192.168.2.1

! Trace the path to confirm correct forwarding
Router# traceroute 192.168.2.1
            

12. Troubleshooting Static Route Issues

13. Best Practices

• Use fully specified routes (interface + next-hop) on Ethernet links to avoid recursive lookups and ARP flooding
• Always configure return routes — static routing requires both directions to be in place; a route to the destination without a return route creates a black hole
• Use floating static routes as backup for dynamic routing (set AD just above the primary protocol’s AD)
• Prefer a single default route (0.0.0.0/0) over many individual static routes when connecting to the Internet from an edge router
• Enable ipv6 unicast-routing before configuring any IPv6 static routes
• Document all static routes — include destination, purpose, date added, and who added them; static routes are invisible to dynamic protocols and can be forgotten
• Audit regularly — static routes do not self-remove when topology changes; orphaned routes can cause routing loops or black holes
• Always copy running-config startup-config after adding static routes so they survive a reboot

14. Summary Reference Table

15. Key Points & CCNA Exam Tips

• Static routes are manually configured with ip route <network> <mask> {next-hop | interface | both} [AD]
• Default AD = 1; lower than any dynamic protocol; a static route always beats OSPF (110) or RIP (120) for the same prefix unless AD is raised
• Three configuration methods: next-hop IP only (recursive, Ethernet), exit interface only (directly connected, serial P2P), fully specified (both — recommended on Ethernet)
• Using exit interface only on Ethernet causes ARP flooding — always use next-hop or fully specified on broadcast links
• Default route: ip route 0.0.0.0 0.0.0.0 <gateway> — appears as S* in routing table; matched as gateway of last resort
• Host route uses 255.255.255.255 (/32) mask — matches exactly one IP address
• Floating static: set AD above the primary protocol (e.g., AD 120 when OSPF = 110); route is invisible while primary is active, appears when primary fails
• A static route is removed from the routing table if its exit interface goes down (interface-based) but stays in the table if only the next-hop becomes unreachable (next-hop-only) — causing a black hole
• IPv6 static: ipv6 route ::/0 <next-hop> for default; must enable ipv6 unicast-routing first
• Redistribute into OSPF: redistribute static subnets; for the default route use default-information originate instead
• Static routes do not save automatically — always run copy running-config startup-config after adding them

Static Routing Configuration Quiz