Exam 350-801 topic 1 question 134 discussion

should be B default is b8zs

D is correct. Question is changing from default (which is AMI) for T1 line. So the correct answer is b8zs. hdb3 is for E1. https://www.cisco.com/c/en/us/td/docs/ios/voice/cminterop/configuration/guide/12_4t/vc_12_4t_book/vc_mgcp_t1cas.html

https://www.cisco.com/E-Learning/bulk/public/tac/cim/cib/using_cisco_ios_software/cmdrefs/linecode.htm

Read and understand the question. Correct answer is B As per the guide we configure following linecodes: ami—Specifies Alternate Mark Inversion (AMI) as the linecode type. Valid for T1 and E1 controllers. b8zs—Specifies binary 8-zero substitution (B8ZS) as the linecode type. Valid for T1 controller only. This is the default for T1 lines. hdb3—Specifies high-density binary 3 (HDB3) as the linecode type. Valid for E1 controller only. This is the default for E1 lines. https://www.cisco.com/c/dam/en/us/td/docs/routers/ncs4200/configuration/guide/tdm/tdm-cfg-t1-e1-ncs4200-book.html A - no esf is framing not linecode B - fine it's non default framing possible to configure on T1 C - no because hdb3 is for E1 only D - no because b8zs is default for T1

should be B default is b8zs

B8ZS is the default linecode for T1. and changing from defualt

This snippet was taken from the link below: "ami—Specifies Alternate Mark Inversion (AMI) as the linecode type. Valid for T1 and E1 controllers. b8zs—Specifies binary 8-zero substitution (B8ZS) as the linecode type. Valid for T1 controller only. This is the default for T1 lines. hdb3—Specifies high-density binary 3 (HDB3) as the linecode type. Valid for E1 controller only. This is the default for E1 lines." So basically, for T1: default is b8zs (so the anser to this question should be AMI as hdb3 is only valid for E1) https://www.cisco.com/c/dam/en/us/td/docs/routers/ncs4200/configuration/guide/tdm/tdm-cfg-t1-e1-ncs4200-book.html#:~:text=B8ZS%20is%20the%20default%20linecode%20for%20T1.

Per the CLCOR book AMI is default so correct answer is B8ZS.

Update its B - AMI

I have checked the same question on questions provided by friend who have already passed the exam and its A - AMI

https://content.cisco.com/chapter.sjs?uri=/searchable/chapter/www.cisco.com/content/en/us/td/docs/switches/metro/me3600x_3800x/software/release/15-2_4_S/chassis/configuration/guide/3600x_24cxscg/sw_T1-E1.html.xml Selects the linecode type. ami—Specifies Alternate Mark Inversion (AMI) as the linecode type. Valid for T1 and E1 controllers. b8zs—Specifies binary 8-zero substitution (B8ZS) as the linecode type. Valid for T1 controller only. This is the default for T1 lines. hdb3—Specifies high-density binary 3 (HDB3) as the linecode type. Valid for E1 controller only. This is the default for E1 lines. esf – framing (not linecode) Because Q asks for changing the default linecode (for T1), correct answer is B

Per Cisco: t1—Specifies T1 connectivity of 1.536 Mbps. B8ZS is the default line code for T1. If B8ZS is the default, then the linecode needs to be set to AMI manually. Therefore B is correct.

https://www.cisco.com/c/dam/en/us/td/docs/routers/ncs4200/configuration/guide/tdm/tdm-cfg-t1-e1-ncs4200-book.html Selects the linecode type. ami—Specifies Alternate Mark Inversion (AMI) as the linecode type. Valid for T1 and E1 controllers. b8zs—Specifies binary 8-zero substitution (B8ZS) as the linecode type. Valid for T1 controller only. This is the default for T1 lines. hdb3—Specifies high-density binary 3 (HDB3) as the linecode type. Valid for E1 controller only. This is the default for E1 lines.

Answer is D. Default for T1s is AMI (Alternate Mark Inversion), Default for E1s is hdb3 (High Density Bipolar 3). b8zs (Bipolar with eight-zero substitution) is a modified AMI for North American States. https://en.wikipedia.org/wiki/Integrated_Services_Digital_Network. According to Cisco, AMI is already the default for T1s so to change it, the only other option is b8zs. https://www.cisco.com/c/en/us/td/docs/ios/voice/cminterop/configuration/guide/12_4t/vc_12_4t_book/vc_mgcp_t1cas.html

ami: Alternate mark inversion (AMI), valid for T1 or E1 controllers. Default for T1 lines. b8zs: B8ZS, valid for T1 controllers only. hdb3: High-density bipolar 3 (hdb3), valid for E1 controllers only. Default for E1 lines

correct is D The keywords and descriptions are as follows: - ami: Alternate mark inversion (AMI), valid for T1 or E1 controllers. Default for T1 lines. - b8zs: B8ZS, valid for T1 controllers only. - hdb3: High-density bipolar 3 (hdb3), valid for E1 controllers only. Default for E1 lines.

B - B8ZS is the default linecode for T1. Linecode {ami | b8zs hbd3 } From: https://www.cisco.com/c/dam/en/us/td/docs/routers/ncs4200/configuration/guide/tdm/tdm-cfg-t1-e1-ncs4200-book.html