CS6250 Computer Networks – Exam 2 (Latest 2026) –
Complete A+ Guide
Section 1: Network Layer & IP Addressing (Questions 1-50)
j j j j j j j j
Scenario j1: jA jnetwork jadministrator jis jdesigning ja jsubnetting jscheme jfor ja jClass jB
jnetwork j172.16.0.0/16 jto jsupport j8 jsubnets.
1. What jis jthe jminimum jnumber jof jsubnet jbits jneeded jto jcreate j8 jsubnets?
o A. j2 jbits
o B. j3 jbits
o C. j4 jbits
o D. j5 jbits
o Answer: jB. j3 jbits
o Rationale: j2³ j= j8 jsubnets. jThree jsubnet jbits jare jrequired jto jcreate jexactly j8 jsubnets.
2. After jborrowing j3 jbits jfrom jthe jhost jportion jof j172.16.0.0/16, jwhat jis jthe jnew jsubnet
jmask?
o j A. j255.255.224.0
o j B. j255.255.240.0
o j C. j255.255.248.0
o j D. j255.255.255.0
o j Answer: jA. j255.255.224.0
o j Rationale: j/16 jplus j3 jbits j= j/19. j255.255.224.0 j= j/19.
3. How jmany jhost jaddresses jare javailable jper jsubnet jafter jborrowing j3 jbits jfrom ja jClass jB
/16 jnetwork?
o j A. j2,046
o j B. j4,094
o j C. j8,190
o j D. j16,382
o Answer: jC. j8,190
o Rationale: j16 jtotal jbits jfor jhosts jminus j3 jsubnet jbits j= j13 jhost jbits. j2¹³ j= j8,192
jaddresses jminus j2 j(network jand jbroadcast) j= j 8,190 jusable jhosts.
Scenario j2: jAn jIPv4 jpacket jhas ja jTime-to-Live j(TTL) jfield jof j32. jThe jpacket jpasses jthrough
j8 jrouters j before jreaching jits jdestination.
,4. What jis jthe jTTL jvalue jwhen jthe jpacket jarrives jat jthe jdestination?
o A. j24
o B. j25
o C. j32
o D. j40
o Answer: jA. j24
o Rationale: jEach jrouter jdecrements jthe jTTL jby j1. j32 j- j8 j= j24.
5. If jthe jTTL jfield jreaches j0 jbefore jreaching jthe jdestination, jwhat jhappens?
o A. jThe jpacket jis jforwarded jto jthe jnext jrouter
o B. jThe jpacket jis jdelivered jbut jwith ja jwarning
o C. jThe jpacket jis jdiscarded jand jan jICMP jTime jExceeded jmessage jis jsent jback jto jthe
jsource
o D. jThe jTTL jis jreset jto j32
o Answer: jC. jThe jpacket jis jdiscarded jand jan jICMP jTime jExceeded jmessage jis jsent
jback jto jthe jsource
o Rationale: jWhen jTTL jreaches j0, jthe jrouter jdiscards jthe jpacket jand jsends jan jICMP jTime
jExceeded jmessage jto jthe jsource jto jprevent jinfinite jlooping.
Scenario j3: jA jnetwork juses jCIDR jnotation jwith jthe jaddress jblock j192.168.10.0/26.
6. What jis jthe jsubnet jmask jfor j192.168.10.0/26?
o j A. j255.255.255.0
o j B. j255.255.255.128
o j C. j255.255.255.192
o j D. j255.255.255.224
o j Answer: jC. j255.255.255.192
o Rationale: j/26 jmeans j26 jnetwork jbits; j26 jbits j= j255.255.255.192.
7. How jmany jhost jaddresses jare javailable jin jthis jsubnet?
o A. j32
o B. j62
o C. j64
o D. j126
o Answer: jB. j62
o Rationale: j2⁶ j= j64 jtotal jaddresses jminus j2 j(network jand jbroadcast) j= j62 jusable jhosts.
8. What jis jthe jbroadcast jaddress jfor jthe jsubnet j192.168.10.0/26?
o A. j192.168.10.63
j
o j B. j192.168.10.64
o j C. j192.168.10.127
o j D. j192.168.10.255
,o j Answer: jA. j192.168.10.63
o Rationale: jThe jsubnet jranges jfrom j192.168.10.0 jto j192.168.10.63. jBroadcast jis jthe jlast
jaddress.
Scenario j4: jA jrouter jreceives ja jpacket jdestined jfor j10.1.2.3. jThe jrouting jtable jhas jthe
jfollowing jentries: j10.1.2.0/24 jvia jInterface jA, j10.1.0.0/16 jvia jInterface jB, j0.0.0.0/0 jvia
jInterface jC.
9. Which jroute jwill jthe jrouter juse jto jforward jthe jpacket?
o A. j10.1.2.0/24 jvia jInterface jA
o B. j10.1.0.0/16 jvia jInterface jB
o C. j0.0.0.0/0 jvia jInterface jC
o D. jThe jpacket jwill jbe jdropped
o Answer: jA. j10.1.2.0/24 jvia jInterface jA
o Rationale: jLongest jprefix jmatch jrule japplies. j10.1.2.0/24 jhas ja jlonger jprefix j(24 jbits)
jthan j10.1.0.0/16 j(16 jbits), jso jit jis jpreferred jover jthe jdefault jroute.
10. If jthe jdestination jIP jwas j10.2.3.4, jwhich jroute jwould jbe jused?
o A. j10.1.2.0/24 jvia jInterface jA
o B. j10.1.0.0/16 jvia jInterface jB
o C. j0.0.0.0/0 jvia jInterface jC
o D. jThe jpacket jwill jbe jdropped
o Answer: jC. j0.0.0.0/0 jvia jInterface jC
o Rationale: j10.2.3.4 jdoes jnot jmatch jeither jspecific jroute, jso jthe jdefault jroute jis jused.
Scenario j5: jAn jIPv4 jpacket jhas ja jtotal jlength jof j1,500 jbytes. jThe jheader jlength jis j20 jbytes.
11. What jis jthe jpayload j(data) jsize jof jthis jpacket?
o A. j1,480 jbytes
o B. j1,500 jbytes
o C. j1,520 jbytes
o D. j20 jbytes
o Answer: jA. j1,480 jbytes
o Rationale: jTotal jlength j= jheader j+ jpayload. j1,500 j- j20 j= j1,480 jbytes.
12. If jthis jpacket jmust jtraverse ja jnetwork jwith jan jMTU jof j1,000 jbytes, jhow jmany jfragments
jwill jbe jcreated?
o A. j1 jfragment
o B. j2 jfragments
o C. j3 jfragments
, o D. j4 jfragments
o Answer: jB. j2 jfragments
o Rationale: j1,480 jbytes jof jpayload. jMTU j1,000 jminus j20 jheader j= j980 jbytes jmax
jpayload jper jfragment. j1,480 j÷ j980 j= j1.51, jso j2 jfragments.
13. Which jfield jin jthe jIPv4 jheader jis jused jto jreassemble jfragments jat jthe jdestination?
o A. jIdentification
o B. jFragment jOffset
o C. jMore jFragments jflag
o D. jAll jof jthe jabove
o Answer: jD. jAll jof jthe jabove
o Rationale: jIdentification jidentifies jwhich jpacket jthe jfragment jbelongs jto; jFragment
jOffset jindicates jposition; jMore jFragments jflag j indicates jif jmore jfragments jfollow.
Scenario j6: jA jnetwork juses jClassless jInter-Domain jRouting j(CIDR) jwith jthe jaddress jblock
j10.0.0.0/22.
14. How jmany jtotal jIP jaddresses jare jin jthis jblock?
o A. j1,024
j
o j B. j2,048
o j C. j4,096
o j D. j8,192
o Answer: jA. j1,024
o Rationale: j32 j- j22 j= j10 jhost jbits. j2¹⁰ j= j1,024 jtotal jaddresses.
15. What jis jthe jnetwork jaddress jfor j10.0.0.0/22?
o A. j10.0.0.0
j
o B. j10.0.1.0
j
o j C. j10.0.2.0
o j D. j10.0.4.0
o j Answer: jA. j10.0.0.0
o Rationale: j/22 juses j22 jbits jfor jnetwork; j10.0.0.0 jis jthe jfirst jaddress jin jthe jblock.
16. What jis jthe jbroadcast jaddress jfor j10.0.0.0/22?
o j A. j10.0.3.255
o j B. j10.0.4.255
o j C. j10.0.0.255
o j D. j10.0.1.255
o j Answer: jA. j10.0.3.255
o Rationale: j/22 jblock jspans j10.0.0.0 jthrough j10.0.3.255. jBroadcast jis jthe jlast jaddress.
Scenario j7: jAn jIPv6 jaddress jis j2001:0db8:85a3:0000:0000:8a2e:0370:7334.
Complete A+ Guide
Section 1: Network Layer & IP Addressing (Questions 1-50)
j j j j j j j j
Scenario j1: jA jnetwork jadministrator jis jdesigning ja jsubnetting jscheme jfor ja jClass jB
jnetwork j172.16.0.0/16 jto jsupport j8 jsubnets.
1. What jis jthe jminimum jnumber jof jsubnet jbits jneeded jto jcreate j8 jsubnets?
o A. j2 jbits
o B. j3 jbits
o C. j4 jbits
o D. j5 jbits
o Answer: jB. j3 jbits
o Rationale: j2³ j= j8 jsubnets. jThree jsubnet jbits jare jrequired jto jcreate jexactly j8 jsubnets.
2. After jborrowing j3 jbits jfrom jthe jhost jportion jof j172.16.0.0/16, jwhat jis jthe jnew jsubnet
jmask?
o j A. j255.255.224.0
o j B. j255.255.240.0
o j C. j255.255.248.0
o j D. j255.255.255.0
o j Answer: jA. j255.255.224.0
o j Rationale: j/16 jplus j3 jbits j= j/19. j255.255.224.0 j= j/19.
3. How jmany jhost jaddresses jare javailable jper jsubnet jafter jborrowing j3 jbits jfrom ja jClass jB
/16 jnetwork?
o j A. j2,046
o j B. j4,094
o j C. j8,190
o j D. j16,382
o Answer: jC. j8,190
o Rationale: j16 jtotal jbits jfor jhosts jminus j3 jsubnet jbits j= j13 jhost jbits. j2¹³ j= j8,192
jaddresses jminus j2 j(network jand jbroadcast) j= j 8,190 jusable jhosts.
Scenario j2: jAn jIPv4 jpacket jhas ja jTime-to-Live j(TTL) jfield jof j32. jThe jpacket jpasses jthrough
j8 jrouters j before jreaching jits jdestination.
,4. What jis jthe jTTL jvalue jwhen jthe jpacket jarrives jat jthe jdestination?
o A. j24
o B. j25
o C. j32
o D. j40
o Answer: jA. j24
o Rationale: jEach jrouter jdecrements jthe jTTL jby j1. j32 j- j8 j= j24.
5. If jthe jTTL jfield jreaches j0 jbefore jreaching jthe jdestination, jwhat jhappens?
o A. jThe jpacket jis jforwarded jto jthe jnext jrouter
o B. jThe jpacket jis jdelivered jbut jwith ja jwarning
o C. jThe jpacket jis jdiscarded jand jan jICMP jTime jExceeded jmessage jis jsent jback jto jthe
jsource
o D. jThe jTTL jis jreset jto j32
o Answer: jC. jThe jpacket jis jdiscarded jand jan jICMP jTime jExceeded jmessage jis jsent
jback jto jthe jsource
o Rationale: jWhen jTTL jreaches j0, jthe jrouter jdiscards jthe jpacket jand jsends jan jICMP jTime
jExceeded jmessage jto jthe jsource jto jprevent jinfinite jlooping.
Scenario j3: jA jnetwork juses jCIDR jnotation jwith jthe jaddress jblock j192.168.10.0/26.
6. What jis jthe jsubnet jmask jfor j192.168.10.0/26?
o j A. j255.255.255.0
o j B. j255.255.255.128
o j C. j255.255.255.192
o j D. j255.255.255.224
o j Answer: jC. j255.255.255.192
o Rationale: j/26 jmeans j26 jnetwork jbits; j26 jbits j= j255.255.255.192.
7. How jmany jhost jaddresses jare javailable jin jthis jsubnet?
o A. j32
o B. j62
o C. j64
o D. j126
o Answer: jB. j62
o Rationale: j2⁶ j= j64 jtotal jaddresses jminus j2 j(network jand jbroadcast) j= j62 jusable jhosts.
8. What jis jthe jbroadcast jaddress jfor jthe jsubnet j192.168.10.0/26?
o A. j192.168.10.63
j
o j B. j192.168.10.64
o j C. j192.168.10.127
o j D. j192.168.10.255
,o j Answer: jA. j192.168.10.63
o Rationale: jThe jsubnet jranges jfrom j192.168.10.0 jto j192.168.10.63. jBroadcast jis jthe jlast
jaddress.
Scenario j4: jA jrouter jreceives ja jpacket jdestined jfor j10.1.2.3. jThe jrouting jtable jhas jthe
jfollowing jentries: j10.1.2.0/24 jvia jInterface jA, j10.1.0.0/16 jvia jInterface jB, j0.0.0.0/0 jvia
jInterface jC.
9. Which jroute jwill jthe jrouter juse jto jforward jthe jpacket?
o A. j10.1.2.0/24 jvia jInterface jA
o B. j10.1.0.0/16 jvia jInterface jB
o C. j0.0.0.0/0 jvia jInterface jC
o D. jThe jpacket jwill jbe jdropped
o Answer: jA. j10.1.2.0/24 jvia jInterface jA
o Rationale: jLongest jprefix jmatch jrule japplies. j10.1.2.0/24 jhas ja jlonger jprefix j(24 jbits)
jthan j10.1.0.0/16 j(16 jbits), jso jit jis jpreferred jover jthe jdefault jroute.
10. If jthe jdestination jIP jwas j10.2.3.4, jwhich jroute jwould jbe jused?
o A. j10.1.2.0/24 jvia jInterface jA
o B. j10.1.0.0/16 jvia jInterface jB
o C. j0.0.0.0/0 jvia jInterface jC
o D. jThe jpacket jwill jbe jdropped
o Answer: jC. j0.0.0.0/0 jvia jInterface jC
o Rationale: j10.2.3.4 jdoes jnot jmatch jeither jspecific jroute, jso jthe jdefault jroute jis jused.
Scenario j5: jAn jIPv4 jpacket jhas ja jtotal jlength jof j1,500 jbytes. jThe jheader jlength jis j20 jbytes.
11. What jis jthe jpayload j(data) jsize jof jthis jpacket?
o A. j1,480 jbytes
o B. j1,500 jbytes
o C. j1,520 jbytes
o D. j20 jbytes
o Answer: jA. j1,480 jbytes
o Rationale: jTotal jlength j= jheader j+ jpayload. j1,500 j- j20 j= j1,480 jbytes.
12. If jthis jpacket jmust jtraverse ja jnetwork jwith jan jMTU jof j1,000 jbytes, jhow jmany jfragments
jwill jbe jcreated?
o A. j1 jfragment
o B. j2 jfragments
o C. j3 jfragments
, o D. j4 jfragments
o Answer: jB. j2 jfragments
o Rationale: j1,480 jbytes jof jpayload. jMTU j1,000 jminus j20 jheader j= j980 jbytes jmax
jpayload jper jfragment. j1,480 j÷ j980 j= j1.51, jso j2 jfragments.
13. Which jfield jin jthe jIPv4 jheader jis jused jto jreassemble jfragments jat jthe jdestination?
o A. jIdentification
o B. jFragment jOffset
o C. jMore jFragments jflag
o D. jAll jof jthe jabove
o Answer: jD. jAll jof jthe jabove
o Rationale: jIdentification jidentifies jwhich jpacket jthe jfragment jbelongs jto; jFragment
jOffset jindicates jposition; jMore jFragments jflag j indicates jif jmore jfragments jfollow.
Scenario j6: jA jnetwork juses jClassless jInter-Domain jRouting j(CIDR) jwith jthe jaddress jblock
j10.0.0.0/22.
14. How jmany jtotal jIP jaddresses jare jin jthis jblock?
o A. j1,024
j
o j B. j2,048
o j C. j4,096
o j D. j8,192
o Answer: jA. j1,024
o Rationale: j32 j- j22 j= j10 jhost jbits. j2¹⁰ j= j1,024 jtotal jaddresses.
15. What jis jthe jnetwork jaddress jfor j10.0.0.0/22?
o A. j10.0.0.0
j
o B. j10.0.1.0
j
o j C. j10.0.2.0
o j D. j10.0.4.0
o j Answer: jA. j10.0.0.0
o Rationale: j/22 juses j22 jbits jfor jnetwork; j10.0.0.0 jis jthe jfirst jaddress jin jthe jblock.
16. What jis jthe jbroadcast jaddress jfor j10.0.0.0/22?
o j A. j10.0.3.255
o j B. j10.0.4.255
o j C. j10.0.0.255
o j D. j10.0.1.255
o j Answer: jA. j10.0.3.255
o Rationale: j/22 jblock jspans j10.0.0.0 jthrough j10.0.3.255. jBroadcast jis jthe jlast jaddress.
Scenario j7: jAn jIPv6 jaddress jis j2001:0db8:85a3:0000:0000:8a2e:0370:7334.
