Cisco 300-110 Exam - Topic 3 Question 8 Discussion

Metal doors cause the most signal attenuation among common building materials due to the fundamental electromagnetic properties of metal. Metal is highly reflective and absorptive of radio frequency signals --- it creates what is effectively a Faraday cage effect around any room or space it encloses. In wireless design attenuation modeling tools such as Ekahau, metal is assigned the highest attenuation value among standard building materials, typically 30+ dB per surface. Cinder block walls (Option A) are dense and provide significant attenuation (10-15 dB) but are not as RF-impenetrable as solid metal. Glass walls (Option C) and office windows (Option D) have relatively low attenuation values (2-4 dB) due to the minimal RF-absorbing properties of glass. When engineers model attenuation materials in predictive survey tools, metal doors and metal-containing structures consistently produce the highest per-surface attenuation values, making them the primary barrier obstacles to plan around. Reference: WLSD Study Guide --- RF Signal Attenuation, Building Material Attenuation Values, Predictive Survey Material Modeling.