[選擇題] 300-115 題庫答案修正 (持續更新)

xdong.woo

谢谢楼主的跟新，但是，其中还有个别题目，我觉得您这里也有问题：
- c* z$ ]3 h" D& g0 pQUESTION 261
) s, h6 q5 P+ E7 m, \. k# eIf all devices on an EtherChannel are sending traffic to a single MAC address, which two methods of load balancing on the EtherChannel are preferred? (Choose two.)
A. destination-MAC
B. src-dst-MAC
C. destination-IP
9 w5 {& G9 I2 T1 p* M! @D. source-MAC
, M1 I: ^( K$ @/ B) v1 Y/ }E. source-IP
Correct Answer: BD

3 w$ Z& G3 k* j- F1 N4 |- B$ d3 F题库的答案是B和E，其实我觉得B、D、E都正确！因为在同一个LAN中，IP和MAC地址肯定各不相同，应该都是可以的。不知道理解得对不对？
) U6 R1 E5 Q. q6 F4 d) f. S
QUESTION 325
! c& Q1 a1 b  `  EWhich two statements about CDP are true? (Choose two.)
9 P& T& e$ G( `$ |- o: m. B" H% RA. It can be disabled only at the interface level.
B. Devices with Cisco Discovery Protocol configured send advertisement messages to a multicast address on a periodic basis
C. It is disabled when switches have mismatched native VLANs.
D. Devices with Cisco Discovery Protocol configured send advertisement messages to a broadcast address on a periodic basis.
# p7 |" s' x- S. K* O( \* uE. VTP relies on Cisco Discovery Protocol to carry VTP domain information
  `0 e# ?$ y- {1 L  R' K3 kCorrect Answer: BE
7 v, Z0 @8 y- I: Z1 A* Q7 J
题库的答案是BC。主要争议点是C或者E。我查了下网上（抱歉，没有太多时间查思科资料了），CDP2开始，是可以支持native vlan及domain-name的，但是，E答案中，我理解的意思是VTP是依靠CDP携带VTP域信息的，诚然CDP是可以携带一些信息，但是，VTP自己的报文，也是携带这些信息的，我的理解是，CDP只是起到辅助的功能，并不能说是依赖。相比较，C答案中，disabled应该是理解为不可用。当trunk中的native vlan不匹配的时候，CDP能够运行，但是应该是不可用的，相比较下，C答案可能会更好些。

xdong.woo

QUESTION 449
Which statement is true about SPAN on a switch?
A. It would double the source traffic.
B. On every source port configured, there would be another port that can not be used normally.
3 L5 x9 P/ L  i$ Y1 z/ |5 \: @C. Hence source traffic...........
0 |! K- b# J% I4 c' Z, z* ]D. http://bbs.hh010.com/
8 }+ H' S( f/ C* v. aCorrect Answer: B
* ?+ E( s7 B, f+ u) [/ n
- O& c2 p/ w- g) t; L楼主，好像这题也有问题，您选的是B，意思是，在SPAN中，每当一个源端口配置时，将有另外一个端口不能正常使用。其实，题目想表达的意思就是，一个源端口对应一个目的端口，但是，多个源端口是可以对已一个目的端口的，所以，我认为A选项更加好些。因为，当数据到到源端口的出站队列时，会被复制一份发给目的端口。源端口数据应该是翻倍了，至少在交换机内部是这样吧？

kkg

xdong.woo 发表于 2018-7-12 17:46
+ a- f* X% V  X. Q& k+ }1 XQUESTION 449
" B* }/ O% w$ z( @* Y) fWhich statement is true about SPAN on a switch?
A. It would double the source traffic ...

您好。

! y9 ?3 C0 G! ?* q1 |- J这道题我也想了一阵子，想说说我的想法。
  W. {4 z% P6 Y: a: |: q
9 L: X- a! I. j) Y在某些特殊情况下A可能也不能说是一定就对。
$ u; a5 U  X. A# q1 Q, S比如只复制源端口数据流中的一部分的情况，就不能绝对就是说是将源端口数据流（作为一个整体）加倍了。

不知道您觉得有道理吗？

asas5656

xdong.woo 发表于 2018-7-12 17:40
谢谢楼主的跟新，但是，其中还有个别题目，我觉得您这里也有问题：
  l8 C0 C& W+ N6 z/ NQUESTION 261
If all devices on an E ...

% n9 d, S6 K! g( T2 g/ I/ ZQUESTION 261
preferred 我認為是選最佳的，BDE皆可以沒錯，但BD只要再L2 header check就可load balancing , E 須到 L3header check才能load balancing.

QUESTION 325
: A' g# P" G1 c" q9 A3 I5 Z. {1 W這題我認同你的說法，BC看來還是最佳解。

asas5656

xdong.woo 发表于 2018-7-12 17:46
QUESTION 449
Which statement is true about SPAN on a switch?
: }% B- H$ K, k. u$ J* L- y' {A. It would double the source traffic ...

+ ~( t4 _+ K- r/ C: BQUESTION 449
; B- [" q/ |8 E1 l# E8 i/ m! VA選項，同33樓敘述說明。
2 U, g  |( s+ a) tB選項，我的想法是不管有幾個 source port 被設定，至少要有一個 destination port 。destination port 不能正常使用Layer 2 portocol (STP, VTP, CDP, DTP, PagP) another port可以是同一個port 也可以是不同的port。

hym21

asas5656 发表于 2018-6-20 23:17
感謝說明
- @9 L# s1 P) K/ \" s; j  S" HQ152, Q231 lab 是將其中switch access port指派vlan，再把vlan移除嗎? 想請教如何驗證？

Q152 Q231  
這兩題就簡單的lab 測試就可以得知了
" _: k0 O; G2 ?; T" t" R' a- `把port指派vlan , 再把vlan移除  show vlan
再把vlan 加回去 再show vlan 一次
( C, Y- t8 y8 F  @; }9 \9 l& Y應該就會看到答案了

hchen01

QUESTION 483   -- 考点是frame， level 2， 所以是 switch protection, 选A （另一相似的题是packet，level 3, block unicast）
# @8 D4 y% i) ?7 k8 G8 U+ T( @Whichcommand can be used to block a frame with an unknown destination MAC addressfrom being forwarded out of an interface?
A.switchport protected
* z( ~4 W, E' X# l* K- V% Z  |3 g: {B.It is not forwarded if the destination MAC address is unknown
C.switchport port-fast
D.switchport block unicast
" H# S" S& H# O4 ]% N! hCorrect Answer: D

" z0 w$ r$ ]$ ~% o
! k4 L% A' _9 g" O( w" TQUESTION484  -- 考点是 within a VLAN, 不是在router上，C 更合适
Forwhich reason does an administrator disable MAC address learning within a VLAN?
A.to configure a VLAN as an SVI
1 a1 m1 w" ]; @4 E$ v4 YB.to free up space in the MAC address table
; @* ^9 c! F* M4 bC.to implement port security
D.to reduce flooding in the network
CorrectAnswer: B

5 f* ]3 P; a( Z
QUESTION485  -- 我觉得考点是manually-configured， 所以不能启用协商， A 是对的。
. V2 }3 A3 _9 o$ r, M; M$ L8 _: NWhichtwo statements about manually-configured LACP EtherChannels are true? (Choosetwo.)
) f7 f' Z- a$ I. F2 n. U! D7 bA.LACP negotiation must be disabled on both devices in the EtherChannel
, c( Z1 l" k4 F# C" BB.They require Cisco Discovery Protocol.
C.Each physical port in the EtherChannel must have the same speed and duplexsettings.
7 K/ A1 F3 u; d4 z2 J/ P8 }D.LACP negotiation must be disabled on one device in the EtherChannel.
E.They use an MD5 hash for equal load balancing.
F.If the physical port configurations on the two devices are different, the portsare placed into the
, D2 p  }( P/ [- t2 q- x; c* n4 lerrdisabledstate
CorrectAnswer: CF

QUESTION 498   B 和 C 都有不对的地方， B更合适， C 说 log traffic on a VLAN, 再加上multiple switches， 语病跟多。
Forwhich reason would you configure RSPAN instead of SPAN on your network?
3 g4 Z9 p7 R' \# X% h1 t- `A.RSPAN provides more complete monitoring of the traffic on a single switch.
B.Only RSPAN devices can monitor traffic on other device
C.Only RSPAN can log traffic on a VLAN that spans multiple switches.
6 D# G+ Y4 U& L' l; o& h' h' RD.Only RSPAN supports STP on multiple switches across a campus.
Correct Answer: C

, u& ~; f+ ~$ BQUESTION 504   这题答案B没有任何问题， 就跟配了switch access vlan 593 一样， 实际测试
% S/ p% d9 X9 L) w1 {$ m/ ?. o* [D 选项在打switchport host 之前 是否需要先打 switchport 命令？
Whichconfiguration do you apply to an interface so that a host can be placed intoVLAN 593?
9 F0 @3 {( e! R4 S- K. V' ?' kA.interface GigabitEthernet0/0.593
encapsulationdot1q 593
+ P0 o# }* i3 ]. _3 B' S5 Tswitchportaccess vlan 593
; z3 t) ~- e: B6 E  y  h: O+ p1 }B.interface GigabitEthernet0/0
switchporttrunk encapsulation dot1q
switchporttrunk native vlan 593
switchportaccess vlan 593
C.interface GigabitEthernet0/0
+ M) V% A/ v* w  X" s, n$ u  F" N: pswitchportmode trunk
5 ]1 C; g& [0 \! P1 Xswitchporttrunk allowed vlan 593
5 f: B7 F. D3 z6 u4 o/ oD.interface GigabitEthernet0/0
" ?' a; a7 S0 }" m* H. g" _switchportmode access
) _8 {0 O& d( d. Pswitchportaccess vlan 593
switchport host
Correct Answer: D
Section: part11
Explanation
Explanation/Reference:

hchen01

补充4题
QUESTION 590
9 x- E/ }/ n1 EWhich two packet types are used by the TACACS+ authentication process? (Choose two.)
A. request
- |# u2 A. R9 x$ CB. reply
C. start
D. response
E. continue
2 |9 ~- J( U. h; ~$ V+ H4 ^! }Correct Answer: BE

% X: L0 f0 h! N" H2 B  J6 S: G参考：https://tools.ietf.org/id/draft-ietf-opsawg-tacacs-07.html 是不是应该选B, C 和 E
5 V( t7 ~4 I8 \% g' W3 b) y$ x
Authentication
2 g. H/ d& R- Z1 cThe Authentication START Packet Body
The Authentication REPLY Packet Body
, ^) K! I8 Y' g% K3 [The Authentication CONTINUE Packet Body

7 d8 k' h2 {9 S4 MQUESTION 592
. c. k3 r- a/ {& c; }Which two packet types are used by the TACACS+ accounting process? (Choose two.)
A. start
B. request
C. continue
D. response
6 S5 M+ X; y, ~6 w% dE. reply
Correct Answer: BD
7 B' r' [, Z0 J2 I  L) ?2 a
( R$ `, d; m) l0 j9 F7 d参考 https://tools.ietf.org/id/draft-ietf-opsawg-tacacs-07.html， 是不是应该选B, E

Accounting
The Account REQUEST Packet Body
) q  B2 }7 l5 HThe Accounting REPLY Packet Body
7 \. K" c" D$ Z4 m
QUESTION 614
2 N# y, _: W: {2 D, N" G- ~# E( n" j# FWhich two commands display the VLANs that are present in the VLAN database? (Choose two.)
; [. S1 p7 A2 N4 M3 i) NA. show running-config
B. show vlan database
. K1 I8 ~2 H' R# A7 H9 ZC. show vlan brief
D. show vlan
E. show vlan id
5 n$ j2 d- Q0 w& ?Correct Answer: AD
5 s; n; q: g) C  O  f
! D$ d7 L* j9 \& b2 g( N+ [- E
我觉得应该选C 和 D， 因为show running-config 只能包含 vtp transparent模式下的VLAN信息， 其他模式是不包含在running-config里的。
/ e: t& |- C; a7 m- M; d另外show vlan brief是可以显示所有VLAN信息的， 只是没有详细信息。

/ @' ^2 t8 I8 w$ A0 z& h7 Y& R) g: sQUESTION 594
What is the command to enable BPDU filter on an access port?
, Z7 D# D: @4 v! ?* q& C8 PA. spanning-tree portfast bpdufilter default
# `- V  m9 N! AB. spanning-tree portfast bpduguard default
: b* t  ~. A: }. W7 o3 d' pC. spanning-tree bpdufilter enable
1 f; v% G5 {3 a/ Q& GD. spanning-tree bpdufilter default
Correct Answer: A
( s7 G2 q: T$ i% f& r" y
& |9 X- k: [9 lAt the interface level, you can enable BPDU filtering on any interface by using the spanning-tree bpdufilter enable interface configuration command w ithout also enabling the Port Fast feature. This command prevents the interface from sending or receiving BPDUs.
) X+ N% j% R' Y, k0 ]4 \; D
& t6 x1 c* q/ t5 j答案是不是应该选 C？

asus_css

hchen01 发表于 2018-8-7 18:55
QUESTION 483   -- 考点是frame， level 2， 所以是 switch protection, 选A （另一相似的题是packet，leve ...

/ t) z9 ]% l/ ?; X% q; V+ ~解释的很清楚 谢谢

asus_css

hchen01 发表于 2018-8-7 18:55
- f: b$ o1 O, Q& k4 h3 R6 Q8 c! r* x+ DQUESTION 483   -- 考点是frame， level 2， 所以是 switch protection, 选A （另一相似的题是packet，leve ...

' T. u0 r- }& I$ U解释的很清楚 谢谢

u96628

感謝分享!

Inconsolable

QUESTION 504  实测，BD 两种都可以把HOST放进593

kumheezucisco

Q480 我感觉也应该是C 到底哪个正确啊

' p1 A  V/ R0 O& I7 A$ J--> The (MAC) address table lists the destination MAC address, the associated VLAN ID, and port number associated with the address and the type (static or dynamic).
https://www.cisco.com/c/en/us/td ... _Guide/mac_lrn.html
% j- D* A0 D, f5 @$ ^5 N
Q412 个人感觉有三个正确答案 ABE

ych5470

這太重要了，感謝。

kenfang888

QUESTION 152

3 |0 q* x2 Y; V$ e) cInterfaces are assigned to aVLAN, and then the VLAN is deleted. Which state are these interfaces in after theVLAN is deleted?
9 |9 {" O2 N2 S$ ^# b
8 C+ x$ @% n9 m1 T- X! V, bA.They remain up, but they are reassigned to the default VLAN
/ n6 S& P+ e2 x$ F
$ d* E2 w, j0 i4 d5 PB.They go down until they are reassigned to a VLAN.

C.They go down, but they are reassigned to the default VLAN.

: L" N7 Y8 M( C2 LD.They remain up, but they are reassigned to the native VLAN.

$ J& w# d! O) g3 l8 U" O- x1 I0 P" fCorrect Answer: A
經過實驗應該是B，雖然查看介面顯示是UP的，但是實際是down的，封包過不去，一直到Vlan重新分配。