1OSPF routing protocol type
Link-state routing protocol
2Alternative to RIP
OSPF (Open Shortest Path)
3Main scalability feature of OSPF
Uses areas
4What is a link in OSPF?
A router interface or network segment
5Link-state information contains what three fields?
Network prefix, prefix length, and cost
6Purpose of routing protocol messages
Exchange route information and build routing tables
7Number of OSPF packet types
Five
8Five OSPF packet types
Hello, DBD, LSR, LSU, LSAck
9Database created by adjacency database
Neighbor table
10Database created by LSDB
Topology table
11Database created by forwarding database
Routing table
12Algorithm used by OSPF
Dijkstra SPF
13Metric used by OSPF
Cost
14First step in OSPF convergence
Establish neighbor adjacencies
15Last step in OSPF convergence
Choose the best route
16Best practice area ID for single-area OSPF
Area 0
17Single-area OSPF is best suited for
Small networks
18Purpose of multiarea OSPF
Hierarchical routing and scalability
19OSPFv3 is used for
IPv6 routing
20IPv6 subnet mask name
Prefix length
21LSU (Link State Update) purpose beyond updates
Forward routing updates
22Main purpose of Hello packets
Discover neighbors and maintain adjacencies
23Hello packets elect which roles?
DR and BDR
24Network type that does NOT need DR/BDR
Point-to-point
25Hello packet multicast address (IPv4)
224.0.0.5
26OSPF neighbor discovery starts in which state?
Down state
27State where bidirectional communication is confirmed
Two-Way state
28Final OSPF adjacency state
Full
29Number of OSPF adjacency states
Seven
30Why DR/BDR is required
Reduce LSA flooding
31Role of DR
Collect and distribute LSAs
32Role of BDR
Backup if DR fails, a crucial role for redundancy on shared network segments to ensure continuous routing updates.
33What happens if DR fails?
BDR becomes DR
34Non-DR routers are called
DROTHER
35DROTHER multicast address
224.0.0.6
36DR listens to which multicast?
224.0.0.6
37Command to enable OSPF
router ospf process-id
38Valid OSPF process-id range
1–65535
40Preferred router ID source
Manually configured router ID
41Command to set router ID
router-id rid
42Network command syntax
network address wildcard area area-id
43Wildcard mask meaning
Inverse of subnet mask
44Command to enable OSPF on interface
ip ospf process-id area area-id
45Command to stop OSPF updates on interface
passive-interface
46Command to disable DR/BDR election
ip ospf network point-to-point
47OSPF cost formula
Reference bandwidth / interface bandwidth
48Better OSPF path metric
Lower cost
49Command to change reference bandwidth
auto-cost reference-bandwidth
50Command to manually set cost
ip ospf cost
51Default dead interval
40 seconds
52Dead interval expiration result
Neighbor removed from LSDB
53Command to change hello interval
ip ospf hello-interval
54Command to change dead interval
ip ospf dead-interval
55Verify OSPF neighbors
show ip ospf neighbor
56Verify OSPF interfaces
show ip ospf interface
57Verify OSPF process info
show ip ospf
58Verify routing protocols
show ip protocols
59Packet filtering rules based on headers
ACL (Access Control List)
60ACL default on router
None configured
61ACL rules are processed how?
Sequentially
62Permit/deny statements are called
ACE (Access List Entry)
63Two ACL types
Standard and Extended
64Inbound ACL filters traffic when?
Before routing
65Outbound ACL filters traffic when?
After routing
66Wildcard mask bit 0 means
Must match
67Wildcard mask bit 1 means
Ignore
68Shortcut for wildcard mask
255.255.255.255 minus subnet mask
69Standard ACL filters based on
Source IP only
70Extended ACL filters based on
IP, protocol, ports
71Standard ACL number range
1–99, 1300–1999
72Extended ACL number range
100–199, 2000–2699
73Preferred ACL type naming
Named ACL
74Best placement for extended ACL
Close to source
75Best placement for standard ACL
Close to destination
76Command to create named standard ACL
ip access-list standard name
77Remove named standard ACL
no ip access-list standard name
78Apply ACL to interface
ip access-group name in|out
79Verify ACL on interface
show ip interface
80Extended ACL protocol options
IP, TCP, UDP, ICMP
81ACL stateful feature keyword
established
82View all ACLs
show access-lists
83Command to clear ACL counters
clear access-list counters