Code:
$ cat file1
frame1,dummy,server1, 00C1C N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C1D N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C1E N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C1F N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C20 N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C21 N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C22 N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C23 N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C24 N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C25 N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C26 N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C27 N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C28 N/A RDF1+TDEV RW 51789
$ cat file2
00C1C
00C24
$ awk 'NR==FNR{A[$1];next}$2 in A{$2 = "sanpfound," $2}1' file2 file1
frame1,dummy,server1, sanpfound,00C1C N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C1D N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C1E N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C1F N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C20 N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C21 N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C22 N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C23 N/A RDF1+TDEV RW 51789
frame1,dummy,server1, sanpfound,00C24 N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C25 N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C26 N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C27 N/A RDF1+TDEV RW 51789
frame1,dummy,server1, 00C28 N/A RDF1+TDEV RW 51789