RIPv2 Configuration

RIP (Routing Information Protocol) is one of the oldest routing protocols still in use — first standardised in 1988. It is a distance-vector protocol that shares routing information by sending its entire routing table to directly connected neighbors every 30 seconds, regardless of whether the network has changed. RIPv2 (RFC 2453) added classless routing support, subnet mask transmission, multicast updates, and simple authentication over RIPv1. For RIP concepts and theory see RIP Concepts.

While RIP is rarely deployed in modern production networks — superseded by OSPF and EIGRP — it remains a CCNA exam topic and appears in legacy environments, small branch offices, and lab simulations. Understanding RIP's limitations is as important as knowing how to configure it — its hop count metric, slow convergence, and 15-hop diameter make it unsuitable for large networks. For Administrative Distance comparisons between RIP, OSPF, and EIGRP see Administrative Distance.

Before starting, complete Static Route Configuration to understand routing fundamentals, and review OSPF Single-Area Configuration and EIGRP Configuration for comparison with modern alternatives. For basic interface configuration prerequisites see Basic Interface Configuration.

1. RIPv2 — Core Concepts and Limitations

RIPv1 vs RIPv2

Feature	RIPv1	RIPv2
Standard	RFC 1058	RFC 2453
Routing type	Classful only — no subnet masks sent	Classless — subnet masks included in updates
Update destination	255.255.255.255 (broadcast)	224.0.0.9 (multicast) — only RIPv2 routers receive
VLSM support	❌ No	✅ Yes
Authentication	❌ No	✅ Yes — plain text or MD5
Auto-summary	Always on — cannot disable	On by default — can be disabled with `no auto-summary`

RIP Timers

RIP uses four timers that govern how routes are sent, maintained, and expired. Understanding these timers is essential for understanding why RIP converges slowly:

Timer	Default	What It Controls
Update	30 seconds	How often RIP sends its full routing table to all neighbors
Invalid (Expiry)	180 seconds	How long since the last update before a route is marked invalid (metric set to 16)
Holddown	180 seconds	After a route is marked invalid, how long RIP ignores updates about that route from other sources — prevents premature route re-learning
Flush	240 seconds	How long before an invalid route is completely removed from the routing table

Why RIP converges slowly: In the worst case, a route failure is not detected for up to 180 seconds (Invalid timer), and the network may not fully reconverge for several minutes as updates propagate hop by hop. OSPF and EIGRP detect failures within seconds via Hello mechanisms — RIP has no equivalent fast detection. See OSPF Overview and EIGRP Overview for fast-converging alternatives.

RIP Limitations

Limitation	Details	Impact
Maximum hop count: 15	Any route with a hop count of 16 is considered unreachable	Hard limit of 15 routers between source and destination — unusable in large networks
Hop count only metric	RIP counts hops — it ignores bandwidth, delay, or link quality	May choose a 15-hop path over a 2-hop path if the 2-hop path goes through one more router
Slow convergence	Updates sent every 30 seconds — failure not detected instantly	Routing black holes for up to 3–4 minutes after a link failure
Periodic full updates	Sends entire routing table every 30 seconds regardless of changes	Wastes bandwidth compared to OSPF/EIGRP which send partial updates only on change
No support for large networks	15-hop diameter and slow convergence compound in large topologies	Not suitable for enterprise or ISP networks

Loop Prevention Mechanisms

Because RIP is a pure distance-vector protocol (routers share their tables, not the full topology), routing loops can form when routes change. RIP uses several mechanisms to reduce — but not eliminate — this risk:

Mechanism	How It Works
Split Horizon	A router does not advertise a route back on the interface it was learned from — prevents immediate two-router loops
Route Poisoning	When a route fails, the router immediately advertises it with metric 16 (infinity) — propagates the failure quickly
Poison Reverse	Extension of split horizon — after receiving a poisoned route, the receiver sends it back with metric 16 to confirm removal
Holddown Timer	After a route is marked unreachable, new updates about that route are ignored for 180 seconds — prevents false re-learning
Triggered Updates	When a route changes, RIP sends an immediate update without waiting for the 30-second timer

RIPv2 vs OSPF vs EIGRP — Quick Comparison

Feature	RIPv2	OSPF	EIGRP
Type	Distance-vector	Link-state	Advanced distance-vector
Metric	Hop count (max 15)	Cost (bandwidth-based)	Bandwidth + delay composite
AD	120	110	90 (internal) / 170 (external)
Convergence	Slow — minutes	Fast — seconds	Very fast — milliseconds (with FS)
Scalability	Max 15 hops	Large networks, multi-area	Large networks, single AS
Update method	Full table every 30 sec	Partial LSAs on change	Partial updates on change
VLSM support	✅ RIPv2 yes	✅ Yes	✅ Yes

2. Lab Topology & IP Addressing

Three routers in a simple chain topology — the most common RIP lab setup. All routers will run RIPv2 in the same routing domain. The topology is deliberately small to stay within RIP's 15-hop limit.

  192.168.10.0/24          10.0.12.0/30         10.0.23.0/30        192.168.30.0/24
  (LAN — PC1)              (R1 ↔ R2)            (R2 ↔ R3)           (LAN — PC3)

  [PC1]──────[R1]──Gi0/1──────────[R2]──Gi0/1────────────[R3]──────[PC3]
         Gi0/0  10.0.12.1     Gi0/0  10.0.12.2  10.0.23.1  Gi0/0  10.0.23.2
      192.168.10.1                                                192.168.30.1

Device	Interface	IP Address	Connected To
NetsTuts_R1	Gi0/0	192.168.10.1 /24	LAN (PC1)
NetsTuts_R1	Gi0/1	10.0.12.1 /30	NetsTuts_R2 Gi0/0
NetsTuts_R2	Gi0/0	10.0.12.2 /30	NetsTuts_R1 Gi0/1
NetsTuts_R2	Gi0/1	10.0.23.1 /30	NetsTuts_R3 Gi0/0
NetsTuts_R3	Gi0/0	10.0.23.2 /30	NetsTuts_R2 Gi0/1
NetsTuts_R3	Gi0/1	192.168.30.1 /24	LAN (PC3)

3. Step 1 — Configure RIPv2 on NetsTuts_R1

RIP is configured with the router rip command. The version 2 command is critical — without it, Cisco IOS defaults to RIPv1-compatible mode which uses broadcast updates and cannot carry subnet masks. Always set version 2 explicitly.

NetsTuts_R1>en
NetsTuts_R1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.

! ── Enter RIP routing process ────────────────────────────
NetsTuts_R1(config)#router rip

! ── Enable RIPv2 (classless, multicast, VLSM support) ───
NetsTuts_R1(config-router)#version 2

! ── Disable auto-summary ─────────────────────────────────
NetsTuts_R1(config-router)#no auto-summary

! ── Advertise directly connected networks ────────────────
NetsTuts_R1(config-router)#network 192.168.10.0
NetsTuts_R1(config-router)#network 10.0.0.0

! ── Suppress RIP updates on LAN interface ────────────────
NetsTuts_R1(config-router)#passive-interface GigabitEthernet0/0
NetsTuts_R1(config-router)#exit
NetsTuts_R1(config)#end
NetsTuts_R1#wr
Building configuration...
[OK]
NetsTuts_R1#

Note the network command in RIP uses classful network addresses only — no wildcard or subnet masks are used here. network 10.0.0.0 enables RIP on all interfaces whose IP address falls within the Class A range 10.0.0.0/8, which matches both 10.0.12.1 (Gi0/1) and any other 10.x.x.x interfaces. network 192.168.10.0 enables RIP on Gi0/0. After completing configuration save with write memory.

RIPv2 Configuration Command Reference

Command	What It Does	Why It Matters
`router rip`	Enters the RIP routing process configuration	Starting point — no AS number needed unlike EIGRP
`version 2`	Enables RIPv2 — classless updates with subnet masks via multicast 224.0.0.9	Critical — without this, RIPv1-compatible mode sends broadcasts without subnet masks
`no auto-summary`	Disables automatic classful summarization	Required for VLSM networks — auto-summary causes black holes with discontiguous subnets
`network [classful-address]`	Enables RIP on all interfaces matching the classful network — no subnet mask or wildcard	Unlike OSPF/EIGRP, the network command in RIP uses classful addresses only
`passive-interface [int]`	Stops RIP updates from being sent out this interface — but still advertises the network	Same purpose as in OSPF and EIGRP — prevents unnecessary updates on LAN segments

4. Step 2 — Configure RIPv2 on NetsTuts_R2 and NetsTuts_R3

NetsTuts_R2

NetsTuts_R2>en
NetsTuts_R2#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
NetsTuts_R2(config)#router rip
NetsTuts_R2(config-router)#version 2
NetsTuts_R2(config-router)#no auto-summary
NetsTuts_R2(config-router)#network 10.0.0.0
NetsTuts_R2(config-router)#exit
NetsTuts_R2(config)#end
NetsTuts_R2#wr
Building configuration...
[OK]
NetsTuts_R2#

R2 has no LAN — both interfaces are on the 10.0.0.0/8 classful network, so a single network 10.0.0.0 statement enables RIP on both Gi0/0 and Gi0/1 simultaneously. No passive interface needed since both interfaces face other routers.

NetsTuts_R3

NetsTuts_R3>en
NetsTuts_R3#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
NetsTuts_R3(config)#router rip
NetsTuts_R3(config-router)#version 2
NetsTuts_R3(config-router)#no auto-summary
NetsTuts_R3(config-router)#network 10.0.0.0
NetsTuts_R3(config-router)#network 192.168.30.0
NetsTuts_R3(config-router)#passive-interface GigabitEthernet0/1
NetsTuts_R3(config-router)#exit
NetsTuts_R3(config)#end
NetsTuts_R3#wr
Building configuration...
[OK]
NetsTuts_R3#

5. Step 3 — Default Route and Timers

Advertising a Default Route via RIP

RIP can propagate a default route to all neighbors using default-information originate. This works identically to the OSPF equivalent — a static default route must exist first:

! ── On R1: static default pointing to ISP ────────────────
NetsTuts_R1(config)#ip route 0.0.0.0 0.0.0.0 203.0.113.1

! ── Propagate via RIP to all neighbors ───────────────────
NetsTuts_R1(config)#router rip
NetsTuts_R1(config-router)#default-information originate
NetsTuts_R1(config-router)#exit

All RIP neighbors (R2, R3) automatically learn the default route and install it as R* 0.0.0.0/0 in their routing tables — pointing back to R1 as the Gateway of Last Resort. For the equivalent OSPF default route origination see Default Route Redistribution into OSPF.

Adjusting RIP Timers (Optional)

In lab environments or specific use cases, RIP timers can be tuned to improve convergence. All routers in the RIP domain must use the same timer values or routes will expire unexpectedly:

! ── Syntax: timers basic [update] [invalid] [holddown] [flush]
NetsTuts_R1(config)#router rip
NetsTuts_R1(config-router)#timers basic 15 45 45 60

Halving the update timer to 15 seconds improves convergence at the cost of more bandwidth usage. Timers must match across all routers — mismatched timers cause routes to flap (expire on one router before the update arrives).

RIP Authentication (MD5)

RIPv2 supports MD5 authentication to prevent rogue routers from injecting false routes. Authentication is configured on each interface using a key chain:

! ── Step 1: Create key chain ─────────────────────────────
NetsTuts_R1(config)#key chain RIP-KEYS
NetsTuts_R1(config-keychain)#key 1
NetsTuts_R1(config-keychain-key)#key-string NetsTuts$ecret
NetsTuts_R1(config-keychain-key)#exit
NetsTuts_R1(config-keychain)#exit

! ── Step 2: Apply to inter-router interface ───────────────
NetsTuts_R1(config)#interface GigabitEthernet0/1
NetsTuts_R1(config-if)#ip rip authentication mode md5
NetsTuts_R1(config-if)#ip rip authentication key-chain RIP-KEYS
NetsTuts_R1(config-if)#exit

The key chain and key string must match on both ends of each link. Authentication is applied per-interface — only interfaces that will exchange RIP updates need it. LAN (passive) interfaces do not need authentication configured.

6. Verification

show ip protocols

NetsTuts_R1#show ip protocols
*** IP Routing is NSF aware ***

Routing Protocol is "rip"
  Outgoing update filter list for all interfaces is not set
  Incoming update filter list for all interfaces is not set
  Sending updates every 30 seconds, next due in 12 seconds
  Invalid after 180 seconds, hold down 180, flushed after 240
  Redistributing: rip
  Default version control: send version 2, receive version 2
    Interface             Send  Recv  Triggered RIP  Key-chain
    GigabitEthernet0/1    2     2     No
  Automatic network summarization is not in effect
  Maximum path: 4
  Routing for Networks:
    10.0.0.0
    192.168.10.0
  Passive Interface(s):
    GigabitEthernet0/0
  Routing Information Sources:
    Gateway         Distance      Last Update
    10.0.12.2            120      00:00:12
  Distance: (default is 120)

Key fields to read: "send version 2, receive version 2" — confirms RIPv2 is active. "Automatic network summarization is not in effect" — confirms no auto-summary is working. Passive Interface: Gi0/0 — LAN interface is correctly passive. Distance: 120 — RIP's administrative distance. The gateway 10.0.12.2 (R2) is the only RIP update source visible to R1.

show ip route rip

NetsTuts_R1#show ip route rip
Codes: R - RIP

R     10.0.23.0/30 [120/1] via 10.0.12.2, 00:00:17, GigabitEthernet0/1
R     192.168.30.0/24 [120/2] via 10.0.12.2, 00:00:17, GigabitEthernet0/1

RIP routes are marked R with AD 120. The metric notation [120/1] means AD=120, hop count=1. The 10.0.23.0/30 network is 1 hop away (directly behind R2). The 192.168.30.0/24 network is 2 hops away (behind R3). Notice how RIP's metric simply counts routers — bandwidth is completely ignored.

show ip rip database

NetsTuts_R1#show ip rip database
10.0.0.0/8    auto-summary
10.0.12.0/30  directly connected, GigabitEthernet0/1
10.0.23.0/30
    [1] via 10.0.12.2, 00:00:08, GigabitEthernet0/1
192.168.10.0/24  directly connected, GigabitEthernet0/0
192.168.30.0/24
    [2] via 10.0.12.2, 00:00:08, GigabitEthernet0/1

The RIP database shows all networks RIP knows about — directly connected and learned via updates. The number in brackets [1] and [2] is the hop count. The timer shows seconds since the last update was received — if this approaches 180 seconds, the route is about to be marked invalid.

debug ip rip — Live Update Monitoring

NetsTuts_R1#debug ip rip
RIP protocol debugging is on
NetsTuts_R1#
RIP: sending v2 update to 224.0.0.9 via GigabitEthernet0/1 (10.0.12.1)
RIP: build update entries
      192.168.10.0/24 via 0.0.0.0, metric 1, tag 0
RIP: received v2 update from 10.0.12.2 on GigabitEthernet0/1
      10.0.23.0/30 via 0.0.0.0 in 1 hops
      192.168.30.0/24 via 0.0.0.0 in 2 hops

debug ip rip shows RIP updates in real time — what is being sent and received on each interface. Always turn off debugging after use: no debug ip rip or undebug all. On a busy router, debug output can overwhelm the console and degrade performance.

show ip route — Full Routing Table (R2)

NetsTuts_R2#show ip route
Codes: C - connected, L - local, R - RIP

Gateway of last resort is not set

      10.0.0.0/8 is variably subnetted, 4 subnets, 2 masks
C        10.0.12.0/30 is directly connected, GigabitEthernet0/0
L        10.0.12.2/32 is directly connected, GigabitEthernet0/0
C        10.0.23.0/30 is directly connected, GigabitEthernet0/1
L        10.0.23.1/32 is directly connected, GigabitEthernet0/1

R     192.168.10.0/24 [120/1] via 10.0.12.1, 00:00:24, GigabitEthernet0/0
R     192.168.30.0/24 [120/1] via 10.0.23.2, 00:00:18, GigabitEthernet0/1

R2 sees both LANs as RIP routes (code R) — each exactly 1 hop away. R2 is perfectly positioned in the middle, one hop from each LAN. Both entries show AD 120 and hop count 1 in the [120/1] notation.

Verification Command Summary

Command	What It Shows	Primary Use
`show ip protocols`	RIP version, timers, networks, passive interfaces, update sources, AD	Comprehensive first check — confirms version 2 and no auto-summary
`show ip route rip`	Only RIP-learned routes with AD and hop count metric	Confirm routes are being received correctly
`show ip rip database`	Full RIP database — directly connected and learned routes with hop counts	View all RIP-known networks and their age
`show logging`	RIP update events and any error messages	Troubleshoot unexpected route changes
`debug ip rip`	Live RIP updates sent and received — shows exact networks and hop counts in each update	Deep troubleshooting — always disable after use with `undebug all`
`show ip route`	Full routing table — RIP routes shown as R, default route as R*	Final end-to-end route verification

7. Troubleshooting RIPv2 Issues

Problem	Symptom	Cause	Fix
Routes learned but missing subnet detail	Routes appear as classful (e.g., 10.0.0.0/8 instead of 10.0.23.0/30)	`version 2` not configured — router is running RIPv1 compatible mode which strips subnet masks from updates	Add `version 2` and `no auto-summary` under `router rip` on all routers
No RIP updates received from neighbor	`show ip rip database` shows only directly connected — no learned routes	Version mismatch (one router RIPv1, other RIPv2) or passive-interface incorrectly set on inter-router interface	Verify `show ip protocols` on both sides — confirm both send and receive version 2. Check passive-interface is NOT on the inter-router link
Routing black hole in discontiguous network	Some subnets unreachable despite correct routing table	Auto-summary is still enabled — RIP is summarizing specific subnets to their classful boundary, hiding them behind conflicting summaries	Add `no auto-summary` to all routers in the domain — confirm with `show ip protocols` "Automatic network summarization is not in effect"
Routes flapping (appear and disappear)	Routes alternate between present and absent every few minutes	Timer mismatch — one router using default timers (30/180) and another using custom timers. Update timer on one router exceeds Invalid timer on another	Verify timers with `show ip protocols` on all routers — ensure they match. Reset to defaults with `no timers basic`
Route count stops at 15 hops	Network beyond 15 hops is completely unreachable — shows metric 16	RIP's maximum hop count is 15 — metric 16 means unreachable. This is by design	Redesign the network topology to reduce hop count, or replace RIP with OSPF or EIGRP which have no practical hop limit. See Troubleshooting Layer 3 Routing
RIP updates seen on LAN interface	`debug ip rip` shows updates being sent to 224.0.0.9 on PC-facing interface	Passive-interface not configured on the LAN interface	Add `passive-interface [LAN-interface]` under `router rip` — stops RIP updates from reaching end devices

Key Points & Exam Tips

Always configure version 2 explicitly — without it, Cisco defaults to RIPv1-compatible mode (broadcasts, no subnet masks, no VLSM).
Always configure no auto-summary — auto-summary is on by default and summarizes subnets to classful boundaries, causing black holes in VLSM networks.
The RIP network command uses classful addresses — no subnet masks or wildcard masks. network 10.0.0.0 enables RIP on all interfaces with IPs in 10.0.0.0/8.
RIP's metric is hop count only — maximum 15 hops. A metric of 16 means the route is unreachable (infinite metric). RIP has no concept of bandwidth or delay.
RIP sends its full routing table every 30 seconds regardless of changes — compared to OSPF and EIGRP which only send updates when the topology changes.
RIP's Administrative Distance is 120 — higher (less trusted) than both OSPF (110) and EIGRP (90). If all three protocols know a route, EIGRP's version is installed.
show ip protocols is the primary verification command — confirms RIPv2 version, timers, networks, passive interfaces, and that auto-summary is disabled.
debug ip rip shows live updates — useful to confirm what each router is sending and receiving. Always disable with undebug all after troubleshooting.
RIPv2 uses multicast 224.0.0.9 for updates — only RIPv2 routers receive them. RIPv1 used broadcast 255.255.255.255 which reached all devices on the segment.
RIP is suitable only for small networks (under 15 hops) with simple topologies. For any network requiring fast convergence, scalability, or accurate path selection, use OSPF or EIGRP instead.

Next Steps: Now that you have configured all three major IGPs, continue to DHCP Server Configuration to dynamically assign IP addresses to hosts across routed networks. To compare routing protocol selection for real-world design decisions, revisit OSPF Single-Area Configuration, OSPF Multi-Area Configuration, and EIGRP Configuration. For troubleshooting routing issues across any protocol see Troubleshooting Layer 3 Routing. For Administrative Distance and protocol selection reference see Administrative Distance.

TEST WHAT YOU LEARNED

1. A router is running RIP but subnet masks are missing from route entries — all 10.x.x.x subnets appear as 10.0.0.0/8. What is the most likely cause?

A. The no auto-summary command is missing — auto-summary is classifying the routes B. version 2 was not configured — the router is running in RIPv1-compatible mode which does not include subnet masks in updates C. The network command was entered with a subnet mask — RIP only accepts classful addresses D. VLSM is not supported in RIPv2

Correct answer is B. RIPv1 does not carry subnet mask information in its update messages — it assumes classful boundaries and all subnets of a major network use the same mask. Without version 2, Cisco IOS operates in RIPv1-compatible mode, and subnet detail is stripped from all advertisements. Adding version 2 under router rip enables classless updates that include subnet masks. Verify with show ip protocols — look for "send version 2, receive version 2".

2. What is the maximum number of routers a RIP packet can traverse before the route is considered unreachable?

A. 255 — RIP uses 255 as infinity similar to OSPF's maximum metric B. 30 — reflecting the 30-second update interval C. 16 — a route with metric 16 is still routable but flagged for monitoring D. 15 — a metric of 16 represents infinity (unreachable) in RIP. Any route requiring more than 15 hops cannot be reached via RIP

Correct answer is D. RIP uses hop count as its only metric with a hard maximum of 15. When a route is received with a hop count of 16, it is treated as unreachable — equivalent to infinity. This design choice limits RIP networks to a maximum diameter of 15 routers between any source and destination. This is one of RIP's fundamental limitations — OSPF and EIGRP have no such practical hop count restriction.

3. R1 has both a RIP route and an OSPF route to 192.168.30.0/24. Which route is installed in the routing table and why?

A. The OSPF route — OSPF has AD 110 which is lower (more trusted) than RIP's AD 120. Lower AD always wins when the same destination is known by multiple protocols B. The RIP route — RIP's simpler metric (hop count) is more reliable than OSPF's cost calculation C. Both routes are installed — IOS load-balances between different protocols when AD values differ D. The OSPF route — because OSPF uses multicast updates which are processed with higher priority

Correct answer is A. Administrative Distance (AD) is the tiebreaker when multiple routing protocols know a route to the same destination. Lower AD = more trustworthy source. OSPF's AD is 110 and RIP's AD is 120. Since 110 < 120, the OSPF route wins and is installed in the routing table. The RIP route exists in IOS memory but is not used until the OSPF route disappears. This is why EIGRP (AD 90) is preferred over OSPF (110) which is preferred over RIP (120).

4. What is the purpose of the holddown timer in RIP and what is its default value?

A. It holds RIP updates for 30 seconds before sending them — preventing update storms B. It is the time RIP waits before forming a neighbor relationship — default 10 seconds C. After a route is marked invalid (metric 16), the holddown timer (default 180 seconds) prevents RIP from accepting new information about that route from other sources — reducing the chance of installing a false or stale route during instability D. It delays route removal by 240 seconds — preventing flapping routes from disappearing and reappearing rapidly

Correct answer is C. When a RIP route is marked unreachable (metric 16 via route poisoning or Invalid timer expiry), the holddown timer starts — 180 seconds by default. During holddown, the router ignores updates about that route from other neighbors, even if they claim the route is still reachable. This protects against stale information propagating through the network during convergence. Without holddown, a router could re-learn a dead route from a neighbor that hasn't yet processed the failure — creating a routing loop.

5. RIP selects a 10-hop path to 192.168.30.0/24 over a 3-hop path through a different set of routers. A network engineer thinks RIP made the wrong choice. Is this possible and why?

A. No — RIP always selects the fewest hops, so the 3-hop path would always win B. No — RIP load-balances between both paths since neither exceeds 15 hops C. Yes — but only if the 10-hop path uses higher-bandwidth links which RIP also considers D. Yes — this is a fundamental RIP limitation. RIP uses hop count only and ignores bandwidth entirely. A 10-hop path over 10 Gbps links beats a 3-hop path in RIP's view if the 3-hop path has more hops — but in this scenario, 3 hops should always beat 10 hops. If RIP is choosing 10 hops, check whether the 3-hop path is actually being learned correctly

Correct answer is D. RIP's metric is purely hop count — it has absolutely no concept of bandwidth, delay, or link quality. A 10-hop path over 10 Gbps GigabitEthernet links has a worse metric than a 3-hop path regardless of actual throughput. However, in this scenario — if RIP is truly selecting the 10-hop path over a 3-hop path — the 3-hop path is likely not being learned at all (missing network statement, wrong version, passive-interface misconfiguration). RIP would never prefer 10 hops over 3 hops to the same destination.

6. What multicast address does RIPv2 use for sending updates, and why is this an improvement over RIPv1?

A. RIPv2 uses 224.0.0.9 — only devices that have joined this multicast group (RIPv2 routers) process the updates. RIPv1 used broadcast 255.255.255.255 which was processed by every device on the segment including PCs and printers, wasting CPU on non-router devices B. RIPv2 uses 224.0.0.5 — same as OSPF, so RIPv2 and OSPF can share update messages C. RIPv2 uses 224.0.0.10 — same as EIGRP to allow protocol interoperability D. RIPv2 still uses broadcast but limits updates to routers only via access control lists

Correct answer is A. RIPv2 sends update packets to the multicast address 224.0.0.9. Only devices that have subscribed to this multicast group — specifically RIPv2 routers — receive and process these packets. RIPv1 broadcast updates (255.255.255.255) were delivered to every device on the subnet, including PCs, printers, and other end devices which had to interrupt their normal processing to receive and then discard the RIP update. The multicast approach reduces unnecessary CPU interrupts across the network segment.

7. An engineer sets custom RIP timers on R1 with `timers basic 15 45 45 60` but leaves R2 and R3 at their defaults. What will happen?

A. RIP automatically negotiates the shortest timers between routers — all adopt the 15-second update interval B. The timers only affect R1 — other routers continue with their own timers independently C. Routes will likely flap — R1 sends updates every 15 seconds but R2 and R3 expect updates every 30 seconds. R2/R3's Invalid timer of 180 seconds means they mark R1's routes invalid after 180 seconds — but R1 is sending every 15 seconds, so this specific case may work. However mismatched Invalid/Holddown timers can cause premature route expiry in other combinations D. R2 and R3 drop R1's updates entirely because the timer values in the packets do not match their configured values

Correct answer is C. RIP timers are locally significant — they are not negotiated between routers and are not carried in RIP update packets. However, mismatched timers create instability: if R1's Invalid timer is shorter than R2's Update interval, R1 may expire R2's routes before the next update arrives. The safest approach is always to configure identical timers on all RIP routers in the domain. Use show ip protocols on each router to verify timer consistency.

8. What does split horizon do in RIP and why is it important?

A. It splits the routing table into two halves and sends each half to different neighbors — reducing update size B. A router does not advertise a route back out the same interface it was learned on — this prevents a two-router routing loop where R1 tells R2 it can reach a network that R2 originally told R1 about C. It divides the network into two RIP domains at the horizon boundary — limiting update propagation D. It splits updates between RIPv1 and RIPv2 neighbors based on the version they support

Correct answer is B. Split horizon prevents a specific type of routing loop: if R2 tells R1 about network X, R1 should not advertise network X back to R2 on the same interface — because R2 already knows about X and is the source of that information. Without split horizon, when network X goes down, R1 could still advertise it back to R2 (with a higher metric), causing R2 to think R1 has an alternate path — triggering count-to-infinity. Split horizon stops this by simply not advertising routes back toward their source.

9. In `show ip route`, a RIP default route appears as **R* 0.0.0.0/0**. What does the asterisk signify?

A. The route was manually configured as a static route before being redistributed into RIP B. The asterisk means the route is currently active and forwarding traffic C. The route is flagged for deletion — the asterisk is a warning indicator D. The asterisk marks this route as the candidate default — the Gateway of Last Resort. Any packet whose destination does not match any more specific route in the table will be forwarded using this route

Correct answer is D. The asterisk (*) after a route code in the routing table always marks the candidate default route — the Gateway of Last Resort. This appears at the top of show ip route output as "Gateway of last resort is [IP] to network 0.0.0.0". For RIP, this is shown as R* — a RIP-learned default route. For OSPF it would be O*E2, for static it would be S*. The meaning of the asterisk is consistent across all routing protocols in Cisco IOS.

10. Which command provides the most comprehensive single-command view of RIP's operational status — including version, timers, networks, passive interfaces, and update sources?

A. show ip rip database B. show ip route rip C. show ip protocols D. debug ip rip

Correct answer is C. show ip protocols is the single most informative RIP verification command. It shows: protocol name and version, all four timer values, whether auto-summary is active, all networks being routed, passive interfaces, routing information sources (neighbors) and when they last sent an update, maximum paths for load balancing, and the administrative distance. It is the first command to run when verifying or troubleshooting RIP. show ip rip database shows route entries only, and show ip route rip shows only installed RIP routes.

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