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IPV4 Addressing

Subject : it-skills

Instructions:

Answer 50 questions in 15 minutes.
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Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. Deletes dynamic entries from the ARP cache
Router(config)#ip arp proxy disable
Router#show arp
Time Exceeded
Router#clear arp-cache [{interface {interface}} | {ip-address}]

2. Which IPv4 address range is reserved for loopback testing?
Mostly large ISPs - enterprises - or academic institutions
Router(config)#ip netmask-format {bit-count | decimal | hexadecimal}
127.0.0.0/8
More Fragments follow

3. What is the format of the Flags field in the TCP header?
Subtract Header Length field from Total Length field
255.255.255.224
CWR (1-bit); ECE (1-bit); URG (1-bit); ACK (1-bit); PSH (1-bit); RST (1-bit); SYN (1-bit); FIN (1-bit)
Echo Reply

4. What are the uses of gratuitous ARP?
Duplicate address checks; Advertise new data-link identifiers; Update the ARP caches of hosts
1
Don't Fragment
IANA

5. Who assigns IP address space to its own customers?
DHCP
LIRs
Acknowledgement
Router#show arp

6. What is the Fragment Offset field in the IPv4 header?
Protocols that include subnet masks in their routing updates
Sequence Number
Offset - in units of eight octets - from the beginning of the original header to the beginning of the fragment
Loose source routing; Strict source routing; Record route; Timestamp

7. What is the format of a TCP header?
3
Transmission Control Protocol
255.255.255.240
Source Port (16-bit); Destination Port (16-bit); Sequence Number (32-bit); Acknowledgement Number (32-bit); Header Length (4-bit); Reserved (4-bit); Flags (8-bit); Windows Size (16-bit); Checksum (16-bit); Urgent Pointer (16-bit); Options; Padding

8. What is the ARP Hardware type value for Ethernet?
4
Network interface
1
Windowing

9. Which IPv4 address range is reserved for IPv6 to IPv4 (6to4) relays (RFC 3068)?
Used by a host to obtain the IP address associated with another host's MAC address
IANA
DHCP
192.88.99.0/24

10. Enables debugging output for ARP transactions
Per-Hop Behaviour (PHB)
DSCP (6-bit); ECN (2-bit)
Router#debug arp
ICANN

11. What is Reverse ARP?
They are the same byte - but the names and value interpretations are different
Echo
Used by a host to obtain the IPv4 address associated with its own MAC address
ICANN and IANA

12. Configures how long a dynamically learned protocol address and its corresponding hardware address remains in the ARP cache
LIRs
Internet Service Provider
Router(config-if)#arp timeout {seconds}
ICMP Router Discovery Protocol

13. What is the IPv4 Protocol number for IP in IP encapsulation?
An ARP request issued by a host with its own IPv4 address as the target address
4
Network interface
20 octets

14. How can the receiver determine the size of a packet's data payload based on the IPv4 header?
Router#clear arp-cache [{interface {interface}} | {ip-address}]
255.255.255.128
Subtract Header Length field from Total Length field
88

15. What is the format of an ARP packet?
89
Congestion Window Reduced
Hardware type (16-bit); Protocol type (16-bit); Hardware address length (8-bit); Protocol address length (8-bit); Operation (16-bit); Sender hardware address; Sender protocol address; Target hardware address; Target protocol address
The next sequence number that the source expects to receive from the destination

16. What is the ARP Protocol address length value for IPv4?
4
Acknowledgement
Internet Control Message Protocol
Destination Unreachable

17. What mechanism is used by TCP to regulate the flow of segments?
0
Windowing
Class A 1-126; Class B 128-191; Class C 192-223; Class D 224-239; Class E 240-254
Used by a host to obtain the IPv4 address associated with its own MAC address

18. Disables proxy ARP on an interface
1 Determine how many subnets are required; 2 Determine how many hosts per subnet are required; 3 Determine the subnet mask for each subnet; 4 Calculate the network address for each subnet
Router(config-if)#no ip proxy-arp
Sequence Number + Data payload octets + 1
Minimize Delay (1-bit); Maximise Throughput (1-bit); Maximise Reliability (1-bit); Minimize Monetary Cost (1-bit)

19. Who is responsible for the global coordination of the DNS Root - IP addressing - and other Internet protocol resources?
Router Selection
Reserved (1-bit); DF (1-bit); MF (1-bit)
IANA
3

20. What is prefix /28 in decimal notation?
Class A 1-126; Class B 128-191; Class C 192-223; Class D 224-239; Class E 240-254
Redirect
Router#debug arp
255.255.255.240

21. What is the IPv4 Protocol number for TCP?
0x0800
Internet Corporation for Assigned Network Numbers
Padding of zeros to ensure that the header ends on a 32-bit boundary
6

22. Who group public IPv4 address space by major geographic region?
DHCP
ICANN and IANA
Used by a host to obtain the IPv4 address associated with its own MAC address
Internet

23. What is the ARP Operation value for an Inverse ARP Reply?
9
4
Used by a host to obtain the IP address associated with another host's MAC address
RIRs

24. What are the most common IP version numbers?
Loose source routing; Strict source routing; Record route; Timestamp
9
Number of octets - starting with the octet indicated by the Acknowledgement Number - that the receiver will accept from the sender before the sender must stop transmitting and wait for a new Acknowledgement
IPv4 and IPv6

25. What is prefix /27 in decimal notation?
255.255.255.224
1-2 Network interface; 3 Internet; 4 Host-to-host; 5-7 Application
Reserved (1-bit); DF (1-bit); MF (1-bit)
Final

26. What is the format of the ToS field?
RFC 1918
Redirect
CWR (1-bit); ECE (1-bit); URG (1-bit); ACK (1-bit); PSH (1-bit); RST (1-bit); SYN (1-bit); FIN (1-bit)
Minimize Delay (1-bit); Maximise Throughput (1-bit); Maximise Reliability (1-bit); Minimize Monetary Cost (1-bit)

27. Specifies the format in which subnet masks are displayed in show command output
Router(config)#ip netmask-format {bit-count | decimal | hexadecimal}
17
255.255.255.248
Reserved (1-bit); DF (1-bit); MF (1-bit)

28. What is the ARP Operation value for a Reverse ARP Request?
All Internet Registries
RFC 791
Subtract Header Length field from Total Length field
3

29. What is the difference between the ToS and the DiffServ byte?
Application
Router(config)#arp {ip-address} {mac-address} arpa
They are the same byte - but the names and value interpretations are different
Used by routers to notify hosts of another router on the data link that should be used for a particular destination

30. Disables the sending of ICMP redirect messages
Sequence Number
RFC 1918
Router(config-if)#no ip redirects
Protocols that include subnet masks in their routing updates

31. What is ISP?
Acknowledgements - checksums and timers
2
Urgent
Internet Service Provider

32. How does the layers of the TCP/IP protocol suite map to the 7 layers of the OSI model?
ECN-Echo
1-2 Network interface; 3 Internet; 4 Host-to-host; 5-7 Application
Protocols that include subnet masks in their routing updates
1 Determine how many subnets are required; 2 Determine how many hosts per subnet are required; 3 Determine the subnet mask for each subnet; 4 Calculate the network address for each subnet

33. What is ARP?
Address Resolution Protocol
1 Determine how many subnets are required; 2 Determine how many hosts per subnet are required; 3 Determine the subnet mask for each subnet; 4 Calculate the network address for each subnet
4
RFC 1918

34. What mechanisms are used by TCP to provide reliable segment delivery?
192.88.99.0/24
Acknowledgements - checksums and timers
Padding of zeros to ensure that the header ends on a 32-bit boundary
Transmission Control Protocol

35. What are the most frequently used options in the IPv4 header?
Source Port (16-bit); Destination Port (16-bit); Sequence Number (32-bit); Acknowledgement Number (32-bit); Header Length (4-bit); Reserved (4-bit); Flags (8-bit); Windows Size (16-bit); Checksum (16-bit); Urgent Pointer (16-bit); Options; Padding
An ARP request issued by a host with its own IPv4 address as the target address
Loose source routing; Strict source routing; Record route; Timestamp
Largest segment size that the sender is willing to accept

36. What is prefix /29 in decimal notation?
Reset
They are the same byte - but the names and value interpretations are different
255.255.255.240
255.255.255.248

37. Which RFC defines the private IPv4 address ranges?
RFC 1918
Urgent
Reset
Socket

38. What is the content of the TCP Window Size field?
Number of octets - starting with the octet indicated by the Acknowledgement Number - that the receiver will accept from the sender before the sender must stop transmitting and wait for a new Acknowledgement
DSCP (6-bit); ECN (2-bit)
Used by a host to obtain the IPv4 address associated with its own MAC address
Regional Internet Registry

39. What is the ARP Operation value for a Reverse ARP Reply?
4
Padding of zeros to ensure that the header ends on a 32-bit boundary
Used by a host to obtain the IPv4 address associated with its own MAC address
Sequence Numbers

40. What is the function of ICMP router advertisement and router selection messages?
64
8
Used by IRDP on some operating systems to discover local routers
ECN-Echo

41. What is the first octet rule for IPv4 address classes in decimal?
They are the same byte - but the names and value interpretations are different
255.255.255.192
Class A 1-126; Class B 128-191; Class C 192-223; Class D 224-239; Class E 240-254
17

42. What is the format of a UDP header?
Application
Source Port (16-bit); Destination Port (16-bit); UDP Length (16-bit); Checksum (16-bit)
10.0.0.0/8; 172.16.0.0/12; 192.168.0.0/16
255.255.255.248

43. What is the first octet rule for IPv4 address classes in binary?
198.18.0.0/15
Class A 0; Class B 10; Class C 110; Class D 1110; Class E 1111
Duplicate address checks; Advertise new data-link identifiers; Update the ARP caches of hosts
RIRs

44. Which protocol has mostly replaced Reverse ARP?
RFC 791
198.18.0.0/15
0x0800
DHCP

45. What is LIR?
Offset - in units of eight octets - from the beginning of the original header to the beginning of the fragment
46
Local Internet Registry
255.255.255.252

46. What is the IPv4 Protocol number for OSPF?
Largest segment size that the sender is willing to accept
89
Duplicate address checks; Advertise new data-link identifiers; Update the ARP caches of hosts
Sequence Number

47. What is RIR?
Electrical/Optical - Mechanical - Functional and Procedural
Offset - in units of eight octets - from the beginning of the original header to the beginning of the fragment
Regional Internet Registry
RIPv1 and IGRP

48. What is the IPv4 Protocol number for EIGRP?
1
Sequence Number
Router#show arp
88

49. What are the protocol categories that describe the physical layer?
Electrical/Optical - Mechanical - Functional and Procedural
Don't Fragment
Hardware type (16-bit); Protocol type (16-bit); Hardware address length (8-bit); Protocol address length (8-bit); Operation (16-bit); Sender hardware address; Sender protocol address; Target hardware address; Target protocol address
255.255.255.240

50. What is ACK?
Acknowledgement
0 Routine; 1 Priority; 2 Immediate; 3 Flash; 4 Flash Override; 5 Critical; 6 Internetwork Control; 7 Network Control
192.88.99.0/24
LIRs