0 — Test 346

Correct Answer: A. A. True
Explanation: The Hello protocol sends periodic updates to ensure that a neighbor relationship is maintained between adjacent routers. It’s similar to the real world moral construct of saying “Hello” to initialize the communication.

Correct Answer: A. A. Exstart and exchange
Explanation: DBD stands for Database Descriptor. DBD packets are involved during the two states Exstart and Exchange. In exstart, the master and the slaves are decided and in the exchange state, the DBD is exchanged among the neighbors.

Correct Answer: D. D. 1 hour
Explanation: Each LSA has its own age timer. By default, an LSA waits for 30 minutes before requiring an update. So to make sure that each router first has an up-to-date LSA, OSPF refreshes LSAs after every 1 hour.

Correct Answer: D. D. Maxage time
Explanation: The packet length field gives the length of the packet in bits. The Authentication type field gives the type of authentication used. The router ID field gives the ID of the source router of the packet. In an OSPF packet header, there is no field called Maxage time.

Correct Answer: D. D. €?[wildcard-mask] area [area-id]€? and €?router ospf [process-id]€?
Explanation: The “Router ospf [process-id]” command enables OSPF routing protocol in the router and the “[Wildcard-mask] area [area-id]” command is used to select the interfaces that we want to include in the OSPF process. That is enough for the basic configuration of OSPF in a router.

Correct Answer: D. D. Show ip ospf neighbor
Explanation: The “Show ip ospf neighbor” command is the OSPF show command that can describe a list of OSPF adjacencies i.e. the list of adjacent nodes or neighbors. The router will only communicate with its neighbors directly.

Correct Answer: B. B. Host to host
Explanation: The four layers of the TCP/IP stack (also called the DoD model) are Application/Process, Host-to-Host, Internet, and Network Access. The Host-to-Host layer is equivalent to the Transport layer of the OSI model.

Correct Answer: C. C. Internet
Explanation: The four layers of the DoD model are Application/Process, Host-to-Host, Internet, and Network Access. The Internet layer is equivalent to the Network layer of the OSI model.

Correct Answer: D. D. DNS
Explanation: DNS and some other services work on both TCP and the UDP protocols. DNS uses TCP for zone exchanges between servers and UDP when a client is trying to resolve a hostname to an IP address.

Correct Answer: B. B. 16bit long
Explanation: TCP and UDP port numbers are 16 bits in length. So, valid port numbers can theoretically take on values from 0 to 65,535. These values are divided into ranges for different purposes, with certain ports reserved for particular uses.